Exodus 13:11-13

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

12sacrifice every firstborn male offspring to the Lord. The firstborn male offspring of each of your animals belongs to the Lord.

13It will cost you a sheep or a goat to buy any firstborn donkey back from the Lord. If you don’t buy it back, then you must break the donkey’s neck. You must also buy every firstborn son back from the Lord.