Exodus 13:6-10

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.

Therefore, you shall keep this ordinance at its appointed time from year to year.