Exodus 13:11-13

11When the Lord brings you into the land of the Canaanites, as he swore to you and to your fathers, and gives it to you,

12then you must give over to the Lord the first offspring of every womb. Every firstling of a beast that you have – the males will be the Lord’s.

13Every firstling of a donkey you must redeem with a lamb, and if you do not redeem it, then you must break its neck. Every firstborn of your sons you must redeem.