Exodus 12:13-15

13Now the blood shall be a sign for you on the houses where you are. And when I see the blood, I will pass over you; and the plague shall not be on you to destroy you when I strike the land of Egypt.

14‘So this day shall be to you a memorial; and you shall keep it as a feast to the Lord throughout your generations. You shall keep it as a feast by an everlasting ordinance.

15Seven days you shall eat unleavened bread. On the first day you shall remove leaven from your houses. For whoever eats leavened bread from the first day until the seventh day, that person shall be cut off from Israel.