On Pesach, many people refrain from eating matzah sheruyah, matzah that has been soaked in water. The Alter Rebbe writes in one of his Responsa1 that “He who acts stringently in this matter is worthy of blessing… for there is ample reason to refrain [from eating matzah sheruyah] because of a possibility of committing a Torah transgression [if the matzah were not fully baked, some flour would come in contact with water].” “Nevertheless,” concludes the Alter Rebbe, “on the last day of the holiday [i.e., on Acharon Shel Pesach, the eighth day of Pesach], he who acts leniently for the sake of the joy of the festival — Simchas Yom Tov — does not incur any [spiritual] loss.”

Yet, the custom of the Rebbeim of Lubavitch is that, during the festive meals of Acharon Shel Pesach, they not only act leniently with regard to matzah sheruyah, but actually make a point of eating matzah sheruyah, dipping the matzah into each dish!2

What is the reason for this? The Alter Rebbe merely stated that “he who acts leniently for the sake of the joy of the festival does not incur any loss.” He said nothing about any benefit in doing so. Why then are the Rebbeim so scrupulous about eating matzah sheruyah on Acharon Shel Pesach?

There is a fundamental difference between Pesach and Shavuos with regard to eating leavened products. During Pesach, chametz is absolutely forbidden, but during Shavuos, it is not only permitted, but is actually an obligation — the Shtei HaLechem, the “Two Breads” offered on Shavuos, had to be made of chametz.3

Why this change of attitude regarding leavened dough? Chametz is, after all, symbolic of haughtiness and conceit — a trait so deleterious that it is at the root of all other negative traits.4

During Pesach, when one is first leaving the spiritual straits of Egypt, one must “flee” from chametz. It is “not to be seen”5 and “not to be found.”6

However, this is not so with regard to Shavuos, coming as it does after the spiritual service of Sefiras HaOmer, counting the Omer. For the seven-week period between Pesach and Shavuos, with its service of Sefiras HaOmer, refines and transforms one’s negative traits, including haughtiness and conceit.

Once this refinement and transformation have been accomplished, a person’s spiritual status is such that not only is chametz not held in contempt, but it can — and consequently must — be used for further advancement in Torah and mitzvos, such as “pride in following G‑d’s path.”7

In light of the above, it can be understood that Acharon Shel Pesach indeed bears some similarity to the festival of Sefiras HaOmer with regard to chametz, for Acharon Shel Pesach is celebrated after the first week of counting the Omer, when a person has already refined the most important of the negative emotional traits.

Although the person has not yet attained the state he reaches on Shavuos, when he is able to use chametz itself for a mitzvah, he need no longer be so scrupulous in eating matzah (symbolic of a state of complete self-nullification) that he need worry about the remote possibility of chametz involved in matzah sheruyah.

On the day of Acharon Shel Pesach, a Jew already has the spiritual fortitude required to use as part of his Divine service something that is not at a level of complete nullification. This fortitude finds expression in the eating of matzah sheruyah.

Since it is possible on Acharon Shel Pesach to serve on this spiritual level, it becomes necessary to do so.

This is why eating matzah sheruyah is scrupulously observed on Acharon Shel Pesach, in a manner such that its consumption actually becomes part of the mitzvah of the joy of the festival, bringing about Simchas Yom Tov.

Based on Likkutei Sichos, Vol. XXII, pp. 30-32