Numbers 18:21, 26

“Behold, I have given the children of Levi all the tithes in Israel as an inheritance in return for the work which they perform, the work of the tabernacle of meeting.

“Speak thus to the Levites, and say to them: ‘When you take from the children of Israel the tithes which I have given you from them as your inheritance, then you shall offer up a heave offering of it to the LORD, a tenth of the tithe.