Exodus 12:17-20

17You shall also keep 1the Feast of Unleavened Bread, for on this 2very day I brought your 3multitudes out of the land of Egypt; therefore you shall keep this day throughout your generations as 4a 5permanent ordinance. 186In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty-first day of the month at evening. 19For 7seven days there shall be no dough with yeast found in your houses; for whoever eats anything with yeast, that 89person shall be cut off from the congregation of Israel, whether he is a stranger or a native of the land. 20You shall not eat anything with yeast; in all your dwellings you shall eat unleavened bread.’”