Numbers 18:12-15

12All the best of the fresh [olive] oil, and all the best of the new wine and of the grain, the first fruits of those which they give to the Lord, I give them to you.

13The first ripe fruits of all that is in the land, which they bring to the Lord, shall be yours; everyone in your household who is [ceremonially] clean may eat it.

14Every devoted thing in Israel [everything that has been promised to the Lord with an oath] shall be yours.

15Every firstborn of the womb of all flesh, whether it is man or animal, which they bring to the Lord, shall be yours; nevertheless, the firstborn of man you shall most certainly redeem, and the firstborn of unclean animals you shall redeem.