Exodus 13:10-14

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

“Now when the Lord brings you to the land of the Canaanite, as He swore to you and to your fathers, and gives it to you,

you shall devote to the Lord every firstborn of a womb, and every firstborn offspring of an animal that you own; the males belong to the Lord.

But every firstborn of a donkey you shall redeem with a lamb, but if you do not redeem it, then you shall break its neck; and every firstborn among your sons you shall redeem.

And it shall be when your son asks you in time to come, saying, ‘What is this?’ then you shall say to him, ‘With a powerful hand the Lord brought us out of Egypt, from the house of slavery.