Exodus 13:11-13

Living Bible

¹¹ And remember, when the Lord brings you into the land he promised to your ancestors long ago, where the Canaanites are now living, ¹² all firstborn sons and firstborn male animals belong to the Lord, and you shall give them to him. ¹³ A firstborn donkey may be purchased back from the Lord in exchange for a lamb or baby goat; but if you decide not to trade, the donkey shall be killed. However, you must buy back your firstborn sons.