Wednesday, February 08, 2006

Ancient Hebrew Questions and Answers

Q: which document was authored first between P and D?

A: clearly P and D are distinct documents. Upon critical analysis, one notices differences in language as well as theology. D emphasizes centrality of worship and talks about the "levite priests". D is not concerned with exact dates and numbers or the details of priests and sacrifices like P is. It is almost impossible to believe that they are contemporary documents.

Take, for example the festival of "shavuoth". According to P we must count seven weeks from the morrow of the Sabbath and then bring a new grain offering to God. According to D we count seven weeks from the time that the sickle is first applied to the standing grain. These two counting systems are not compatible and it is therefore very unlikely that both documents
existed simultaneously.

Thus, the only question remains which one was authored first and in what generation they did apply. After extensive research and careful deliberation, I have come to the conclusion that the traditional belief that D was a product of the Josiah days is correct. But I have also found that P is a product of the post-exilic period. As said earlier, it could not have been authored in the waning days of the first temple because that was the D period. It doesn't seem to have been authored during the exile because it is too much concerned with practices that were not executable during the exile. I understand that the exiled people of Judaea undoubtedly had a great concern for preserving their laws traditions and the P document could theoretically be part of that effort. But I see in P more than mere preservation of tradition. The P author was very creative; he attempted to create new formulas of worship and clarify ritual ambiguities. Such an effort seems to be related to actual worship, not just to preserve the memories of bygone days. The laws of the Leviticus are nowhere to be found in the D document, and so P would not be inventing these laws unless it could be applied in real life and that is post-exilic.
What remains a bit more difficult to prove is that P is not a product of the pre-Josiah days, perhaps the days of his grand-grandfather Hezekiah who is also known to have been a yawhist. Against this possibility, you should take note of the following:

* P is an extremely extensive code. It covers virtually everything contained in the ancient JE documents, most of the material covered by D and a host of new priestly material not found in any other document. If these codes already existed in the Deutoronomistic days, they should have been at least partially incorporated in D. For example, the different ways of performing the sacrificial rites for the "Olah", "Shelamim" and "Asham" are elaborated in detail in Leviticus but not mentioned at all in deuteronomy.

* Before Hezekiah's days the yahweh cult barely existed. Sacrifices in the temple were not practiced routinely or regulated. People typically brought their sacrifices to "high places" located in the countryside and dedicated to other gods. In Hezekiah's days, all the high places were abolished and only yahweh was to be worshipped but those revolutionary changes never took root for his son manasseh reversed all of his father's reforms. Thus, it is questionable whether the yahweh priests in Hezekiah's days had enough popular support to produce the kind of work contained in P.

* P mentions the holiday of Yom Kippur and Rosh Hashana, not mentioned in D and not mentioned anywhere else in the bible. There is no evidence that these holidays were ever practiced during the first temple. In fact even the holiday of Pesach and Sukkoth were only practiced during the reign of yahwist kings such as Hezekiah and Josiah.

* The language and mood of P is that of a later stage in the religious development of the ancient Judaeans. The terms of Qahal (congregation), Qodesh vs chalal (holy vs profane), ghedah (assembly/testament), zakar and neqebah (male and female), are all widespread in P but not commonly present in any other documents.

* The book recording the works of the priest Ezekial who lived during the exile shares many common characteristics with the P document. Thus it is believed that he belonged to the school that authored the P document. BTW, Jeremiah, on the other hand, contains many similarities to the D document, thus confirming that D was authored in his days.

Is the tabernacle (mishkan) of the exodus myth or fact?

The way it is described in P is -no doubt- fiction. For one, since the details of the exodus tabernacle or even its very existence is not present in any other document, how could the P author possibly know so many details about it seven centuries later (or more)? Secondly, in P the tabernacle and the tent of meeting (Ohel Moed) are the same but there is no hint in E that the tent of meeting was anything other than a simple tent where Moses convened with god. There is no mention that the ark of the covenant was housed there or that there was any sort of altar located within it (the incense altar) or about it (the olah altar). These are very important details and could not have been accidentally missed by the E author. In this case, I must conclude that E's silence about the function of the tent of meeting as a place of worship as described in P, is evidence that the tent of meeting did not serve that function according to E.

Regardless, the details of the Tabernacle such as that it was made of logs of cedarwood inserted vertically into bases (aden) and covered by multiple textile covers, are fictitious. These details were made up by the P author in an attempt to vivify and idealize the tabernacle. Just like the third temple envisioned by Ezekial never came to pass and all its details were meant to idealize a future perfect temple, so is P's depiction of the Exodus tabernacle an attempt to envision an ideal tabernacle of the past. Note that it was essential for P to depict the orthodox yahweh lifestyle as having originated in the days of Moses. P could not claim that there was a temple in the wilderness, for a temple is a permanent dwelling built in stone and that could not have existed in Moses' days. Instead, P took the Shiloh tabernacle, idealized it and placed it in the wilderness with Moses, merging it with the tent of meeting. Another example where we can see P making up a story in order to legitimize its new program is the story of the Yom Kippur sacrifice in the wilderness as told in Leviticus 16. It is designed to pin the origin of this newly invented holiday to Moses and thus establish its legitimacy.

In my opinion, there definitely is a possibility that the ancient Israelites roamed the wilderness with some sort of mobile shrine. We have no reason to doubt that the Shiloh tabernacle existed in the days of Eli and Samuel 150 years after the exodus and so it is very possible that some sort of tabernacle existed before the Israelites settled in Canaan. However, the role of this proto-tabernacle is what needs to be questioned. According to P, it was a central and vital part of Israelite life in the wilderness. In reality, if it existed it was little more than a haphazardly constructed site where people can sacrifice to some ancient Semitic god (yahweh is a late judaean god that did not exist in the formative years of the Israelite tribes) in times of stress to ensure deliverance and victory in war.

What's up with the three annual festivals?

The three annual festivals are mentioned in both ancient documents of J and E and so it is likely that even before Josiah's days, those who worshipped the god of the Jerusalem temple (whatever name he went by), made a pilgrimage to Jerusalem three times a year at each turning point in the agricultural season. These festivals were named after their respective seasons. The first one was the festival of "abib" (abib literally is a young, green seed-bearing ear of grain). This holiday is celebrated during the flax harvest, in the month of Nisan (Nisan being the Babylonian name of the month adopted by the Jews after the exile). The reason it was called the Abib month in Hebrew is that the stalks of wheat start growing in this month. It is therefore the moth of "tender, green ears of wheat".

The next holiday is celebrated in the month of sivan (the Hebrew name of the month is unknown) and is called the festival of "qatsir" (harvest). This is the month during which the wheat is finally harvested. The next holiday is celebrated in the month of Ethanim (Tishri in Babylonian) and is called the festival of "asiph" (gathering) for in this month people gather their wine and oil from the winepress and oilpress which were situated in the open field. During the summer, farmers were engaged in the process of working the winepress and the oilpress to produce wine and oil. Now that the raining season is about to kick in, the precious juices must be gathered in to the house to protect themt from the winter rain. Wheat may also have remained in the field throughout the summer and must now be brought in to the house. Thus it is called "festival of the gathering".

To summarize, we have the following:

Festival celebrated in the month of tender ears of grain (Abib), Nisan in Babylonian.
Festival celebrated in the month of wheat harvest (qatsir), Sivan in Babylonian.
Festival celebrated in the month of gathering (asiph) or ploughing (charish), Elul or Tishri in Babylonian.

Other names of these festivals, adopted in later days and mentioned in the later documents of D and P are:

festival of Pesach or festival of Matsoth for Abib
festival of shebaghoth or day of bikkurim
festival of Sukkoth or festival of the ploughing season "charish"

Some of these names seem to be mentioned in the ancient J and E documents but if you analyze these instances carefully you realize that those were not the identifying names of the festivals. For example, in the J document Exodus 34:22 its says "you shall make a septuple (consisting of seven) festival in the harvest season of the firstfruits of wheat". The Hebrew word for septuple "Shebeath" was taken to designate the name of the festival, so called because it is celebrated seven weeks after the Abib season. This is how both P and D construed the meaning of septuple, although the precise point in time from which the seven weeks ought to be counted is disputed between P and D; in P it's seven weeks from the morrow of Sabbath and in D it is seven weeks from the time when the sickle is first applied to the grain.

However, I believe that this represents an error on the part of later generations in interpreting the ancient JE documents. It is important to understand that the ancient JE documents were not widely known when they were first authored and finalized in the period of the divided kingdom (eighth century BCE). Furthermore, those documents were authored by the proponents of yahwism and advocated the worship of yahweh only, but in the eighth century BCE the yahweh cult (including the three annual festivals held in Jerusalem) was marginal even in Judah. This is why in 2kings 23:22 it says that "there was not held such a Passover from the days of the judges that judged Israel, nor in all the days of the kings of Israel, nor of the kings of Judah" in description of the pesach held in the time of Josiah circa 630 BCE. If this is indeed the case, then we have the deuteronomistic reformers and --later-- the priestly revivalists trying to reconstruct a dormant religion. They would be reading an ancient text that says something about a septuple festival and interpret that to mean a one day holiday held after seven weeks when in reality the text is talking about a seven day holiday tied to a specific season --that of wheat harvest-- and to nothing else.

What prompted the deuteronomists to invent this utterly erroneous interpretation of "septuple"?

This is debatable. One possibility is that they wanted to make it easier to observe yahwism by only requiring pilgrims to spend one day in Jerusalem during the busy qatsir season (recall, that in the priestly days seven day festivals were literally seven days long, unlike the J definition of a seven-day festival in which work is permitted during the first six days). Another possibility is that they sought to better define the timing of the holiday. Finally, it may have been an earnest mistake. Whatever the background for this misinterpretation of "septuple", I am convinced that the deuteronomist, and later the priestly author following his lead, made a major deviation from the real meaning of septuple.

How do I know that septuple in JE really refers to seven days and not seven weeks?

There are several clues:

* In the J document Exodus 34, it mentions the abib festival first and admonishes worshippers to bring along their firstborn animals to sacrifice to yahweh during the festival: "not to see the face of yahweh emptyhanded". Then it describes the actual festival as containing seven days, the first six days of which are work days, that is, one is not required to be in the temple but may work his field and the seventh day is the rest day. Then a new paragraph begins saying "you shall rest in the ploughing season and in the harvest season" and it goes on describing those two additional festivals saying "you shall make a septuple (consisting of seven) festival in the harvest season of the firstfruits of wheat and the (septuple) festival of the gathering season at the rounding of the year. In other words, it is saying that the same seven day holiday of abib just
described in verse 21 shall also be observed in the harvest season and in the gathering/ploughing season.

* the Hebrew letter he preceding a noun is called the "he hayediah" (he of the known) and designates a specific, known noun, a noun that has already been mentioned previously or is otherwise already known to the listener or reader. In the J document, there is a he in the mention of "festival of the Matsoth" and in the mention of "festival of the Asiph" but there is no he in the mention of "a septuple festival". This is because there is no single septuple festival; rather, all three festivals are septuple festivals. The verse is just saying that the same septuple festival observed in the Abib season should also be observed in the harvest and gathering season. In fact, in the corresponding E document (Exodus 23), there is no mention of the term septuple altogether. The second holiday, which the deuteronomist called "festival of weeks" (Deuteronomy 16:9) and the priestly writer called "day of the firstfruits" (Numbers 28:26), is called "festival of the harvest" in the E document (Exodus 23:16), a term which is mentioned by the J document as well in describing the timing of the festival (bikkurei qatsir chittim), although without the he hayediah. Thus, according to the JE tradition the second festival is a harvest festival, not a septuple festival (as distinguished from other festivals), not a weeks festival and not a firstfruits festival.

* Nowhere in J or E is there any indication that the qatsir festival might be a one-day only celebration. According to our interpretation of the J document, it is saying outright that qatsir is a septuple festival, that is, consisting of seven days. But even if we take the deuteronomist interpretation that it's talking about seven weeks, it still doesn't say that it's a one day only festival. We should therefore logically assume that qatsir is the same kind of festival as abib and
asiph, a seven day festival as described in Exodus 34:21 "six days you may work but on the seventh day you shall rest".

* The Hebrew term "shibeghath" in the J document is spelled using the four hebrew letter shin, beth, ayin, thaw. In accordance with our belief that no cholem vowel should be applied in Hebrew unless a waw is present, the correct pronunciation of this word is shibeghath (or "shibeath" if you choose to pronounce the ayin as an aleph) and not shibeghoth as the masoretes would have it. If the masoretes were right then the word would have had a waw after the ayin indicating the plural and it would therefore mean "weeks" (shebagh or shabuagh being the singular). Without the waw in the word, it simply means an entity of seven or a count of seven, not a week.

How was the ancient festival of Pesach (Abib) observed according to the JE tradition?

As soon as the new moon appeared in the season of abib, the "matsoth festival" commenced. Noone was allowed to eat leavened bread for seven days. However, there was no requirement to refrain from work and be at the temple until the seventh day; during the first six days one may work his field (Exodus 34:21). All male firstborn cattle and sheep (born after the last
annual festival) were dedicated to yahweh, the cattle may not be used to work the field and the wool of the sheep may not be shorn. Those animals constituted the pesach sacrifice and were taken along by the worshipper on his pilgrimage to the temple on the seventh day. Technically, firstborn male humans had to be dedicated to yahweh as well. This is openly stated in the E document (Exodus 13:2) and the priestly author went to great lengths explaining how the ancient Israelites redeemed their firstborn humans by substitution with Levites (Numbers 3:11-51). However, this concept did not have a realistic application since the practice of sacrificing humans to God was not commonly practiced even among the ancient Israelites. Only in very severe circumstances would a person offer up a child as a sacrifice like yiphtach did (Judges 11:30).

Once at the temple, the firstborn animals were slaughtered by the priests as the "Pesach" sacrifice. The blood and fats were given to yahweh (sprinkled or burned on the altar) and the meat and hide were shared between the priest and the worshipper. It is not known precisely how they divided the animal but we do know that both the priest and the worshipper had certain rights to it. In deuteronomy 18:3 it says that priests were entitled to the arm, the cheeks and the belly of all sacrifices brought to the temple. It does not differentiate between the Pesach and other voluntary peace offerings (neder or nedabah). There was probably a similar scheme in place during the J period (eighth century BCE).

While feasting on the Pesach, leavened bread (chamets) may not be eaten; this is the meaning of "you shall not slaughter the blood of my sacrifice with unleavened bread" (exodus 34:25). It means "you shall not eat the meat of my sacrifice along with unleavened bread". Note that Maror, a kind of bitter herb, is not mentioned in the JE documents. The requirement to eat Maror with the Pesach is an addition by P and it is not clear whether this is an unusual requirement or perhaps it's the usual or ritual way of eating sacrificial meat.

The meat of the Pesach had to be consumed on the evening of the seventh day and whatever was left over until the morning had to be burnt (the burning requirement is a priestly addition Leviticus 7:17 and elsewhere). The reasoning behind this bizarre law is not clear. We know, for example, that in the priestly days multiple households "enrolled" on a single Pesach animal so that no meat went to waste (Exodus 12:4) but this practice of sharing the Pesach among several households is the effect of the ancient law requiring that no meat be left over until the morning and not the cause. Perhaps this law was designed to encourage feasting like there's no tomorrow and to discourage frugality. Meat was a precious luxury in ancient Israelite days. Meat was not eaten on a daily basis or even on a weekly basis. When one wanted to eat meat in the Judah of the divided kingdom, he was expected to make a pilgrimage to the temple and share the animal with yahweh and the priests. If worshippers had any desire to salt some of the meat and preserve it for consumption back home, this law was designed to prevent such practice and encourage unbridled consumption of the Pesach meat on the festival day.

It is also possible, that the law was designed to force people to sacrifice at the temple and share the meat with the priests. If they could salt the meat and take it with them back home, then they would not be inclined to share the meat with the priests. Furthermore, the frequency of pilgrimages would decline since people would still have some meat left over at home from their previous sacrifice.

Finally, there is one more point that I should make about the J description of the Pesach. In exodus 34:23 it says "Three times in the year shall all your males see the face of the lord yahweh, the God of Israel". This has traditionally been construed to refer to male humans and "seeing the face of god" was understood simply to be synonymous with worshipping god. I strongly disagree with this, however. This would mean that all male servants and toddlers are required to make the pilgrimage, which is quite burdensome, costly and unreasonable. Rather, it means that all male animals must see the face of God in the form of being sacrificed to God. It is a recapitulation of the required dedication of firstborn animals to yahweh mentioned in verses 19-20 and the intention here is all male "firstborn" animals, not literally all male animals.

"all your males" might also include human firsborns insofar as they could be dedicated to yahweh, but --as mentioned earlier-- since the practice of sacrificing humans to god was not considered appropriate when J was authored and levite priests had already been firmly established in the temple (so that there was no need to to devote firstborn humans to God as priests), the dedication of humans to yahweh was not really practicable. This clause "all your males" might be a leftover from an extremely ancient Semitic religion in which human sacrifice was considered acceptable.

How was Pesach observed according to D and P?

You have probably noticed my description of Pesach being observed on the seventh day and not the first day of the seven day festival. This is unequivocally stated in both J and E. The deuteronomist is the one who changed the sacrificial day of Pesach from the last day to the first day and the priestly writer followed faithfully in his footsteps (somewhat similar to the way the qatsir festival was altered by both D and P). J says openly that on the first six days of the Pesach festival one may work the field and only on the seventh day one is required to rest, that is, make the pilgrimage to the temple and offer up the Pesach sacrifice. How can one possibly work on the first day while simultaneously make a pilgrimage to the temple to sacrifice the Pesach? It is therefore abundantly clear that J is designating the seventh day as the sacrificial day. The first six days are merely counting days towards the seventh day during which chamets may not be eaten.

In E this practice is even more pronounced. It says (Exodus 13:4) "sanctify every newborn human and animal among the children of Israel to me... Today you are emerging (from Egypt) on the new moon of Abib and so once yahweh brings you to the canaanite land... You shall perform those acts of worship (ban against chamets and sanctification of the newborn) on this new moon, thus: six days you shall eat unleavened bread and the seventh day shall be a festival to yahweh... and you shall tell your son on that day (=the seventh day) saying: because of this (act of worship), yahweh did (all those miracles) for me when I emerged from Egypt". The masoretic text reads seven days in Exodus 13:6 but the Septuagint, which represents an older and more reliable Hebrew text, reads six days, just like it is in the J text. Regardless, E says openly that the festival is held on the seventh day and there's no mention of any additional first-day festival like the the priestly writer would have it (Leviticus 23:7-8).

This switch from the seventh day to the first day was not initiated by the priestly author, however. The deuteronomist is the one who started it. In deuteronomy 16:1 "guard the new moon of abib and make a Pesach to yahweh your god (on that day)... and there shall not be left over until the morning from the meat that you sacrifice on the evening of the first day". Thus, the deuteronomist makes the first day celebration of Pesach as clear as JE makes the seventh day.

Ironically, all three sources agree that the seven days are counted from the new moon of abib but the priestly writer changed even that. According to the P document, the festival actually consists of eight days. First comes the day on which the Pesach is offered, in the afternoon
of the fourteenth day of the first month (Exodus 12:6 and Leviticus 23:5). Then comes a seven day holiday from the fifteenth until the twenty-first of the month (Exodus 12:18). The term "first day" which designates the first of the seven days of the Pesach festival in the P document, refers to the fifteenth day of Nisan, not the fourteenth - the day the Pesach is sacrificed. The deuteronomist, on the other hand, does not suggest such a scheme. The deuteronomist insists that the seven days are counted from the new year as mentioned earlier and he also insists that the Pesach is sacrificed on the "first day" of the seven days (Deuteronomy 16:4) and not the day before the first day as specified by P.

How were the JE festivals of Qatsir and Asiph observed?

As pointed out earlier both Qatsir and Asiph are seven-day festivals tied to an agricultural season in the solar year just like Pesach (abib) is tied to the appearance of the tender, green stalks of grain. What is not clear is whether those festivals are tied to lunar months as well. The term Chadash (Chodesh) in ancient Hebrew always means a new moon. It does not refer to a solar month, which is an artificial division of the solar year into twelve parts. We know that Pesach is tied to the solar abib season AND to the lunar new moon that appears in that season, for the text says openly "chodesh ha'abib" (the new moon that falls in the abib season). Are Qatsir and Asiph tied to a new moon in their respective solar seasons as well? in the JE document there is no such suggestion but JE only briefly mentions these festivals and so it is possible that their connection to the new moon within the appropriate agricultural season is taken for granted.

It seems logical to assume that the qatsir and asiph festivals had the same model as the Abib festival, namely, start counting seven days from the new moon day that falls in the appropriate agricultural season and designate the seventh day as the pilgrimage day.

But what about the Pesach offering and the matzah requirement? Did these practices apply to the Qatsir and Asiph festivals as well? Again, the JE document does not clarify this matter and since these traditions were not commonly practiced during the JE period (eighth century BCE or earlier) it is extremely hard to try to reconstruct the precise meaning of these ancient documents.

If we look at Exodus 34:25 "Thou shalt not offer the blood of my sacrifice with leaven; neither shall the sacrifice of the feast of the passover be left unto the morning" we see a parallelism between the first part and second part of this verse. According to this poetic expression, "my sacrifice" and "sacrifice of the feast of passover" are one and the same. Instead of referring to an object by the same name twice, the correct poetic way is to name it slightly differently when referring to it again in the same verse just like we say in English "John excelled in math but he was not proficient in Science"; we don't use the verb "excel" twice. Thus, all sacrifices offered to yahweh on any of the three annual festivals (and possibly all other sacrifices as well) are called Pesach sacrifices and the two cardinal Pesach rules essentially apply to all sacrifices: no leavened bread may be eaten with the meat and no meat may be left over until the following morning.

So we have established that the Pesach animal sacrifice applied to all three JE festivals. Now what about the seven-day matzah requirement? Was there a prohibition against eating chamets for seven days during the Qatsir and Asiph festivals?

According to our understanding that during the first six days of the festival, one was allowed to work their field at home and not be present at the temple, the only defining practice during those days was the abstention from chamets. Thus, the abstention from chamets for six days prior to the actual feast day is integral to any seven day festival, including Qatsir and Asiph.

However, there is a problem with this. We know that only the abib festival was called a "matsoth festival"; this is quite clear in the E document (Exodus 23:15-16) which names the festivals: festival of the unleavened bread, festival of the harvest and festival of the gathering. The question is, why isn't it called "festival of the abib", consistent with the other two festivals that are named after their respective agricultural seasons. It seems that the seven-day matzah rule was somehow unique to the abib festival and it alone was therefore called the matzah festival whereas the other festivals did not have this rule and could therefore not be called so and were therefore named after their agricultural season.

Notwithstanding the ambiguity in the way J expresses himself, I still insist that J really meant for all three festivals to contain a preceding six day ban against chamets. Here's how the document should be interpreted:

"Guard the the festival of matsoth, you shall eat matsoth for seven days, as I have (already) commanded you" - this is a preface. What he's saying here is that whenever a festival to God is celebrated, there should be a seven day ban against chamets. Now he goes on describing the three seasons during which festivals should be held. First comes "the season in the month of abib for in the month of abib you emerged from Egypt.." and then he says that two additional seasonal "matzah" festivals should be held: "In the ploughing season and in the harvest season you shall rest" and he explains "observe a septuple festival at the firstfruit-of-wheat harvest season and observe the gathering festival (which coincides with the ploughing season) at the end of the year". By "the gathering festival" J means "the matzah festival that occurs in the gathering season" (chaj hamatsoth shel asiph).

In support of my theory that all three festivals are meant to be matzah festivals, it should be noted that the priestly author expanded the ban against chamets to virtually all sacrifices brought to yahweh, not just "pesach" animal sacrifices brought on the abib or other annual festivals. In Leviticus 2:11 it states "You shall not make chamets any grain offering brought before yahweh".

In all likelihood, leavened bread was seen by these ancient peoples as contaminated and impure, unfit for a godly sacrifice and inappropriate to be eaten together with the meat of a godly sacrifice, even though they acknowledged that it tasted better. Thus, the ban against chamets originally had nothing to do with the abib festival in particular or with the Exodus. Only in later generations was the ban against chamets attributed to the fact that the Israelites did not have time to let their dough rise when leaving Egypt and thus isolated to the festival of abib since that is when the Israelites left Egypt. This connection was admittedly made by the E author and is clearly articulated in the verses Exodus 12:34-13:10. The other authors D and P followed suit and that's how abib became the only matzah festival (and the only Pesach festival).

When J gives the reason for observing a matzah festival in the Abib season "for in the month of Abib you emerged from Egypt" (Exodus 34:18), he is not giving the reason for the ban against chamets. Rather, he is explaining why the the festival is held in this season. This reasoning is also expressed in E (Exodus 13:4-5) "This day came ye out in the month Abib, and it shall be when the LORD shall bring thee into the land of the Canaanites... that thou shalt keep this service in this month".

Both J and E say in connection with the prohibition against chamets "As I have commanded you" (Exodus 34:18 and 23:15). The question is: where had this command been given before?

Answer: It is in Exodus 13:7 "Matsoth shall be eaten for seven days and you shall not see chamets or sourdough in your entire border". Although this chapter is generally considered to be an E document, this particular verse does not fit in here and I believe it was inserted here from a very ancient source by a late editor of the JE manuscript. The previous verse is not only repetitive of this verse but it actually contradicts this verse if we go by the Septuagint version which reads "six days you shall eat matzah..." But even if we go by the Masorete version, it seems bizarre and repetitious:

verse 6: seven days you shall eat matzah...
verse 7: matsoth shall be eaten for seven days...

Verse 7 should be contrasted with the P document who also admonishes against having any chamets or sourdough in the house (Exodus 12:15 and 12:19). The priestly writer mentions both chamets and sourdough but he says uses the term "it shall not be found" rather than "it shall not be seen". Also, he talks about the house rather than the border. Clearly, verse 7 is a very ancient verse, thus explaining why it talks about a border and not house, since the Israelites presumably lived a nomadic lifestyle then and did not posses any houses. Also, the term seeing instead of finding in verse 7 is also suggestive of its antiquity, for the early tribes always used verbs that were intimately tied with one of the five senses.

I think that in all likelihood, this particular verse was taken from an extremely old document (or more likely stone inscription that was widely known among the contemporary tribes. Everyone knew that there was a seven-day complete ban against chamets while sacrificing to the deity. The J author came to clarify this old tradition and said that three annual festivals should be held and he added some other rules as well. This explains "as I have commanded you" very nicely, as the J author is referring back to a known command in order to provide legitimacy and a solid base for his agenda.