Numbers 18:26-32

26“Speak to the Levites and say to them: You will take one-tenth of the Israelites’ income which I’m giving you as your property. When you do, you must contribute one-tenth of that income as your contribution to the Lord.

27Your contribution will be considered to be grain from the threshing floor  or juice from the winepress.

28So you, too, will contribute one-tenth of your income to the Lord out of all that you receive from the Israelites’ income. You will give the Lord’s contribution to the priest Aaron.

29Out of all the gifts you receive, you must contribute the best and holiest parts to the Lord.

30“Also tell them: When you contribute the best part, your contribution will be considered to be produce from the threshing floor or winepress.

31So you and your households may eat it anywhere, because it’s the wages you receive for your work at the tent of meeting.

32When you contribute the best part, you won’t suffer the consequences of any sin. You won’t be dishonoring the holy offerings given by the Israelites, and you won’t die.”