Numbers 18:28 KJV

26Thus speak unto the Levites, and say unto them, When ye take of the children of Israel the tithes which I have given you from them for your inheritance, then ye shall offer up an heave offering of it for the LORD, even a tenth part of the tithe.

27And this your heave offering shall be reckoned unto you, as though it were the corn of the threshingfloor, and as the fulness of the winepress.

28Thus ye also shall offer an heave offering unto the LORD of all your tithes, which ye receive of the children of Israel; and ye shall give thereof the LORD’s heave offering to Aaron the priest.

29Out of all your gifts ye shall offer every heave offering of the LORD, of all the best thereof, even the hallowed part thereof out of it.

30Therefore thou shalt say unto them, When ye have heaved the best thereof from it, then it shall be counted unto the Levites as the increase of the threshingfloor, and as the increase of the winepress.