Numbers 18:20-23

20And the Lord said to Aaron, "You shall have no inheritance in their land, neither shall you have any portion among them. I am your portion and your inheritance among the people of Israel.

21"To the Levites I have given every tithe in Israel for an inheritance, in return for their service that they do, their service in the tent of meeting,

22so that the people of Israel do not come near the tent of meeting, lest they bear sin and die.

23But the Levites shall do the service of the tent of meeting, and they shall bear their iniquity. It shall be a perpetual statute throughout your generations, and among the people of Israel they shall have no inheritance.