Exodus 13:3

13:3 Moses said to the people, “Remember this day on which you came out from Egypt, from the place where you were enslaved, for the Lord brought you out of there with a mighty hand – and no bread made with yeast may be eaten.

Exodus 13:7

13:7 Bread made without yeast must be eaten for seven days; no bread made with yeast shall be seen among you, and you must have no yeast among you within any of your borders.