Numbers 18:12-15

12“All the best of the olive oil and all the best of the wine and of the wheat, the first fruits of these things that they give to the Lord, I have given to you.

13And whatever first ripe fruit in their land they bring to the Lord will be yours; everyone who is ceremonially clean in your household may eat of it.

14“Everything devoted in Israel will be yours.

15The firstborn of every womb which they present to the Lord, whether human or animal, will be yours. Nevertheless, the firstborn sons you must redeem, and the firstborn males of unclean animals you must redeem.