Numbers 18:23-24

23Only the Levites shall perform the service of the tent of meeting, and they shall 1bear their own guilt; it shall be a permanent statute throughout your generations, and among the sons of Israel 2they shall have no inheritance. 24For the tithe of the sons of Israel, which they offer as an offering to the Lord, I have given to the Levites as an inheritance; therefore I have said concerning them, ‘3They shall have no inheritance among the sons of Israel.’”