Midrash su Esodo 12:34

And the people took their dough before it was leavened … upon their shoulders (Exod. 12:34). This indicates that the dough did not have sufficient time in which to leaven. Similarly, concerning the Messianic days, it states: Who ceaseth to stir from the kneading of the dough until it be leavened (Hos. 7:4). Their kneading troughs (mish’arotam), alludes to the leftover (shi-yu) unleavened bread and bitter herbs. You may interpret it so, but perhaps it does not refer to the remnants of the unleavened bread and bitter herbs, but to the remnants of the Passover sacrifices? However, since Scripture says of the paschal sacrifice: And ye shall let nothing of it remain until the morning (Exod. 12:10), it could not refer to the leftovers of the paschal sacrifices. Upon their shoulders (ibid., v. 34). Did they have no beasts of burden to carry the remnants of the unleavened bread and bitter herbs? After all, it is written: And a mixed multitude went up also with them; and flocks, and herds, even very much cattle (ibid., v. 38)? They did so because they cherished their religious obligations deeply. And so it is written: upon their shoulders.