Exodus 34:18

34:18 “You must keep the Feast of Unleavened Bread. For seven days you must eat bread made without yeast, as I commanded you; do this at the appointed time of the month Abib, for in the month Abib you came out of Egypt.

Exodus 34:25

34:25 “You must not offer the blood of my sacrifice with yeast; the sacrifice from the feast of Passover must not remain until the following morning.