Exodus 12:12-16

For I will go through the land of Egypt on that night, and fatally strike all the firstborn in the land of Egypt, from the human firstborn to animals; and against all the gods of Egypt I will execute judgments—I am the Lord.

The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will come upon you to destroy you when I strike the land of Egypt. Feast of Unleavened Bread

‘Now this day shall be a memorial to you, and you shall celebrate it as a feast to the Lord; throughout your generations you are to celebrate it as a permanent ordinance.

For seven days you shall eat unleavened bread, but on the first day you shall remove dough with yeast from your houses; for whoever eats anything with yeast from the first day until the seventh day, that person shall be cut off from Israel.

And on the first day you shall have a holy assembly, and another holy assembly on the seventh day; no work at all shall be done on them, except for what must be eaten by every person—that alone may be prepared by you.