Exodus 12:17-20 NIV

[17] “Celebrate the Festival of Unleavened Bread, because it was on this very day that I brought your divisions out of Egypt. Celebrate this day as a lasting ordinance for the generations to come. [18] In the first month you are to eat bread made without yeast, from the evening of the fourteenth day until the evening of the twenty-first day. [19] For seven days no yeast is to be found in your houses. And anyone, whether foreigner or native-born, who eats anything with yeast in it must be cut off from the community of Israel. [20] Eat nothing made with yeast. Wherever you live, you must eat unleavened bread.”