Exodus 13:11-13

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

12you are to set apart to Adonai every firstborn from the womb, and every firstborn male animal you have will be Adonai’s.

13Every firstborn donkey you are to redeem with a lamb, and if you do not redeem it, then you are to break its neck. But you are to redeem every firstborn male among your sons.