Exodus 13:11-13

“When the LORD brings you into the land of the Canaanites, as he swore to you and your fathers, and shall give it to you, you shall set apart to the LORD all that first opens the womb. All the firstborn of your animals that are males shall be the LORD’s. Every firstborn of a donkey you shall redeem with a lamb, or if you will not redeem it you shall break its neck. Every firstborn of man among your sons you shall redeem.