Exodus 13:12

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.

Exodus 28:38

28:38 It will be on Aaron’s forehead, and Aaron will bear the iniquity of the holy things, which the Israelites are to sanctify by all their holy gifts; it will always be on his forehead, for their acceptance before the Lord.

Numbers 18:32

18:32 And you will bear no sin concerning it when you offer up the best of it. And you must not profane the holy things of the Israelites, or else you will die.’”

Deuteronomy 15:19

Giving God the Best

15:19 You must set apart for the Lord your God every firstborn male born to your herds and flocks. You must not work the firstborn of your bulls or shear the firstborn of your flocks.