Exodus 12:15-17

Seven 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. On the first day there shall be a holy convocation, and on the seventh day there shall be a holy convocation for you. No manner of work shall be done on them; but that which everyone must eat—that only may be prepared by you. So you shall observe the Feast of Unleavened Bread, for on this same day I will have brought your armies out of the land of Egypt. Therefore you shall observe this day throughout your generations as an everlasting ordinance.