Numbers 18:24-26

24Instead, I give to the Levites as their inheritance the tithes that the Israelites present as an offering to the Lord. That is why I said concerning them: ‘They will have no inheritance among the Israelites.’ ” 25The Lord said to Moses, 26“Speak to the Levites and say to them: ‘When you receive from the Israelites the tithe I give you as your inheritance, you must present a tenth of that tithe as the Lord’s offering.