Deuteronomy 16:1-4

Observe the month of Abib by celebrating the Passover to GOD, your God. It was in the month of Abib that GOD, your God, delivered you by night from Egypt. Offer the Passover-Sacrifice to GOD, your God, at the place GOD chooses to be worshiped by establishing his name there. Don’t eat yeast bread with it; for seven days eat it with unraised bread, hard-times bread, because you left Egypt in a hurry—that bread will keep the memory fresh of how you left Egypt for as long as you live. There is to be no sign of yeast anywhere for seven days. And don’t let any of the meat that you sacrifice in the evening be left over until morning.