Numbers 18:15-20

15I give to you every firstborn animal and male child that people offer to the Lord. But you must pay the price for every firstborn son and for every firstborn male animal that is not clean.

16When they are one month old, you must buy them from me for five shekels of silver each. The shekel must have the same weight as the shekel that the Levites use in God's Holy Tent. There are 20 gerahs in one shekel.

17You must not pay for the firstborn of a cow, a sheep or a goat. Those animals are holy. Splash the blood from those animals on the altar and burn the fat from them. The smell will make the Lord happy.

18And the meat of those animals belongs to you. In the same way, the meat of the ribs and the right back leg of the special gifts that you lift up to me also belong to you.

19I have given all the gifts that the Israelites offer to the Lord to you, your sons and your daughters. That is a rule for all time. That is the Lord's special promise to you and to your descendants for all time.’

20Then the Lord said to Aaron, ‘You priests and your descendants will have no land, like the other tribes do. You will not share in the things that they receive. I myself am the gift that you receive.