Numbers 18:30-32

30Therefore say to the Levites, ‘When you have presented the best part, it will be reckoned to you as the produce of the threshing floor or winepress. 31And you and your households may eat the rest of it anywhere; it is the compensation for your work at the Tent of Meeting. 32Once you have presented the best part of it, you will not incur guilt because of it. But you must not defile the sacred offerings of the Israelites, or else you will die.’”