Numbers 18:23-24

23Only the Levites may serve at the Tabernacle, and they will be held responsible for any offenses against it. This is a permanent law for you, to be observed from generation to generation. The Levites will receive no allotment of land among the Israelites,

24because I have given them the Israelites’ tithes, which have been presented as sacred offerings to the Lord. This will be the Levites’ share. That is why I said they would receive no allotment of land among the Israelites.”