Numbers 18:24-28

24That is because I have given to the Levites the tithes that the Israelites offer to the Lord. I have told them, “You will not receive any land, like the other Israelites do.” I have given the tithes to them instead.’

25The Lord said to Moses,

26‘You must say to the Levites, “You will receive from the Israelites the tithe that I have given to you from them. I have not given any land to you. I have given the tithes to you instead. When you receive those tithes, you must offer one tenth of it to the Lord. That will be a tithe of the tithe.

27This gift will be the same as when a farmer is giving grain or wine to me. It will be special.

28So you will give something to the Lord from the tithes that you receive from the Israelites. You must give that part to Aaron the priest.