Numbers 18:30-32

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.’ ”