Numbers 18:26-32

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. 27Your offering will be reckoned to you as grain from the threshing floor or juice from the winepress. 28In this way you also will present an offering to the Lord from all the tithes you receive from the Israelites. From these tithes you must give the Lord’s portion to Aaron the priest. 29You must present as the Lord’s portion the best and holiest part of everything given to you.’ 30“Say to the Levites: ‘When you present the best part, it will be reckoned to you as the product of the threshing floor or the winepress. 31You and your households may eat the rest of it anywhere, for it is your wages for your work at the tent of meeting. 32By presenting the best part of it you will not be guilty in this matter; then you will not defile the holy offerings of the Israelites, and you will not die.’ ”