Numbers 18:25-32

25The Lord instructed Moses,

26“Speak to the Levites and tell them: When you receive from the Israelites the tenth that I have given you as your inheritance, you are to present part of it as an offering to the Lord  — a tenth of the tenth.

27Your offering will be credited to you as if it were your grain from the threshing floor or the full harvest from the winepress.

28You are to present an offering to the Lord from every tenth you receive from the Israelites. Give some of it to the priest Aaron as an offering to the Lord.

29You must present the entire offering due the Lord from all your gifts. The best part of the tenth is to be consecrated.

30“Tell them further: Once you have presented the best part of the tenth, and it is credited to you Levites as the produce of the threshing floor or the winepress,

31then you and your household may eat it anywhere. It is your wage in return for your work at the tent of meeting.

32You will not incur guilt because of it once you have presented the best part of it, but you must not defile the Israelites’ holy offerings, so that you will not die.”