Numbers 18:24

18:24 But I have given to the Levites for an inheritance the tithes of the Israelites that are offered to the Lord as a raised offering. That is why I said to them that among the Israelites they are to have no inheritance.”

Numbers 18:29

18:29 From all your gifts you must offer up every raised offering due the Lord, from all the best of it, and the holiest part of it.’