Listen for free to MP3 audio of Chapter 18
of the Book of Numbers, KJV

⁷ Therefore thou and thy sons with thee shall keep your priest's office for everything of the altar, and within the vail; and ye shall serve: I have given your priest's office unto you as a service of gift: and the stranger that cometh nigh shall be put to death.
⁸ 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.
⁹ 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.