Exodus 13:2

13:2 “Set apart to me every firstborn male – the first offspring of every womb among the Israelites, whether human or animal; it is mine.”

Exodus 13:12-13

13:12 then 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. 13:13 Every 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.