Numbers 18:21-24

21And to the children of Levi, behold, I have given all the tithes in Israel for an inheritance, for their service which they perform, the service of the tent of meeting.

22Neither shall the children of Israel henceforth come near the tent of meeting, to bear sin and die.

23But the Levite, he shall perform the service of the tent of meeting, and they shall bear their iniquity: it is an everlasting statute throughout your generations. And among the children of Israel shall they possess no inheritance;

24for I have given for an inheritance to the Levites the tithes of the children of Israel, which they offer as a heave-offering to Jehovah; therefore I have said of them, They shall possess no inheritance among the children of Israel.