Deuteronomy 16:3-4

`Thou dost not eat with it any fermented thing, seven days thou dost eat with it unleavened things, bread of affliction; for in haste thou hast come out of the land of Egypt; so that thou dost remember the day of thy coming out of the land of Egypt all days of thy life;

and there is not seen with thee leaven in all thy border seven days, and there doth not remain of the flesh which thou dost sacrifice at evening on the first day till morning.