Old Testament

Exodus 12:14-20
14This day shall be a memorial for you, and you are to celebrate it as a festival to the Lord. Throughout your generations you must celebrate it as a permanent regulation. 15For seven days you shall eat unleavened bread. On the first day you must be sure to remove all yeast from your houses, for whoever eats anything leavened from the first day until the seventh day will be cut off from Israel. 16On the first day you are to have a holy convocation; also on the seventh day there is to be a holy convocation. You shall not do any work, except to prepare what everybody needs to eat. That is all you may do.
17You shall observe the Festival of Unleavened Bread, because on this very day I brought your divisions out from the land of Egypt. You shall observe this day throughout your generations as a permanent regulation. 18In the first month, you shall eat unleavened bread from the evening of the fourteenth day of the month until the evening of the twenty-first day of the month. 19No yeast is to be found in your houses for seven days, for whoever eats something leavened must be cut off from the Israelite community, whether a foreigner or native-born of the land. 20You shall not eat anything leavened. You shall eat unleavened bread in every place you live.