Numbers 18:29

“Moreover you shall speak to the Levites, and tell them, ‘When you take of the children of Israel the tithe which I have given you from them for your inheritance, then you shall offer up a wave offering of it for the LORD, a tithe of the tithe.

Your wave offering shall be credited to you, as though it were the grain of the threshing floor, and as the fullness of the wine press.

Thus you also shall offer a wave offering to the LORD of all your tithes, which you receive of the children of Israel; and of it you shall give the LORD’s wave offering to Aaron the priest.

“Therefore you shall tell them, ‘When you heave its best from it, then it shall be credited to the Levites as the increase of the threshing floor, and as the increase of the wine press.

You may eat it anywhere, you and your households, for it is your reward in return for your service in the Tent of Meeting.

You shall bear no sin by reason of it, when you have heaved from it its best. You shall not profane the holy things of the children of Israel, that you not die.’”