Deuteronomy 16:3-5

New Catholic Bible

³ Do not eat leavened bread, but eat unleavened bread for seven days. This is the bread of affliction, for you had to leave the land of Egypt in haste. Thus, all of your life you will remember the day that you came forth from Egypt. ⁴ There should be no leavened bread in your entire land for seven days. Do not let any of the meat of the sacrifice that was made on the first evening remain until the next morning. ^5 [a]You are not to make the Passover sacrifice in any of the towns that the Lord, your God, has given you.