Numbers 18:26-29

18:26 “You are to speak to the Levites, and you must tell them, ‘When you receive from the Israelites the tithe that I have given you from them as your inheritance, then you are to offer up from it as a raised offering to the Lord a tenth of the tithe. 18:27 And your raised offering will be credited to you as though it were grain from the threshing floor or as new wine from the winepress. 18:28 Thus you are to offer up a raised offering to the Lord of all your tithes which you receive from the Israelites; and you must give the Lord’s raised offering from it to Aaron the priest. 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.’