Numbers 18:23-24

²³And the Levite himself shall perform the service of the tabernacle of witness; and they shall bear their iniquities, it is a perpetual statute throughout their generations; and in the midst of the children of Israel they shall not receive an inheritance.

²⁴Because I have given as a distinct portion to the Levites for an inheritance the tithes of the children of Israel, whatsoever they shall offer to the Lord; therefore I said to them, In the midst of the children of Israel they shall have no inheritance.