Deuteronomy 16:4; Deuteronomy 16:6

4 "For seven days no leaven shall be seen with you in all your territory, and none of the flesh which you sacrifice on the evening of the first day shall remain overnight until morning.

6 but at the place where the LORD your God chooses to establish His name, you shall sacrifice the Passover in the evening at sunset , at the time that you came out of Egypt.