Numbers 18:10 (KJV)

And the Lord spake unto Aaron, Behold, I also have given thee the charge of mine heave offerings of all the hallowed things of the children of Israel; unto thee have I given them by reason of the anointing, and to thy sons, by an ordinance for ever.

This shall be thine of the most holy things, reserved from the fire: every oblation of theirs, every meat offering of theirs, and every sin offering of theirs, and every trespass offering of theirs, which they shall render unto me, shall be most holy for thee and for thy sons.

In the most holy place shalt thou eat it; every male shall eat it: it shall be holy unto thee.

And this is thine; the heave offering of their gift, with all the wave offerings of the children of Israel: I have given them unto thee, and to thy sons and to thy daughters with thee, by a statute for ever: every one that is clean in thy house shall eat of it.

All the best of the oil, and all the best of the wine, and of the wheat, the firstfruits of them which they shall offer unto the Lord, them have I given thee.