Numbers 18:12-15

12All the best of the oil, and all the best of the new wine, and of the wheat, the firstfruits of them which they give to Jehovah, have I given thee.

13The first ripe of everything that is in their land, which they shall bring to Jehovah, shall be thine; every one that is clean in thy house shall eat of it.

14Every devoted thing in Israel shall be thine.

15Everything that breaketh open the womb of all flesh, which they present to Jehovah, of men or of beasts, shall be thine; nevertheless the firstborn of man shalt thou in any case ransom, and the firstborn of unclean beasts shalt thou ransom.