Exodus 13:5-9

And it shall be when the Lord brings you to the land of the Canaanite, the Hittite, the Amorite, the Hivite, and the Jebusite, which He swore to your fathers to give you, a land flowing with milk and honey, that you shall perform this rite in this month.

For seven days you shall eat unleavened bread, and on the seventh day there shall be a feast to the Lord.

Unleavened bread shall be eaten throughout the seven days; and nothing with yeast shall be seen among you, nor shall any dough with yeast be seen among you in all your borders.

And you shall tell your son on that day, saying, ‘It is because of what the Lord did for me when I came out of Egypt.’

And it shall serve as a sign to you on your hand, and as a reminder on your forehead, that the law of the Lord may be in your mouth; for with a powerful hand the Lord brought you out of Egypt.