Deuteronomy 16:3-4

Webster(i) 3 Thou shalt eat no leavened bread with it; seven days shalt thou eat unleavened bread with it, even the bread of affliction; for thou camest forth from the land of Egypt in haste: that thou mayest remember the day when thou camest forth from the land of Egypt, all the days of thy life. 4 And there shall be no leavened bread seen with thee in all thy borders seven days; neither shall there any thing of the flesh, which thou didst sacrifice the first day at evening, remain all night until the morning.