Thematic Bible: Bound to give a tenth of their tithes to the priests

Moreover thou shalt speak unto the Levites, and say unto them, When ye take of the children of Israel the tithe which I have given you from them for your inheritance, then ye shall offer up a heave-offering of it for Jehovah, a tithe of the tithe. And your heave-offering shall be reckoned unto you, as though it were the grain of the threshing-floor, and as the fulness of the winepress. Thus ye also shall offer a heave-offering unto Jehovah of all your tithes, which ye receive of the children of Israel; and thereof ye shall give Jehovah's heave-offering to Aaron the priest. read more.
Out of all your gifts ye shall offer every heave-offering of Jehovah, of all the best thereof, even the hallowed part thereof out of it. Therefore thou shalt say unto them, When ye heave the best thereof from it, then it shall be reckoned unto the Levites as the increase of the threshing-floor, and as the increase of the wine-press. And ye shall eat it in every place, ye and your households: for it is your reward in return for your service in the tent of meeting. And ye shall bear no sin by reason of it, when ye have heaved from it the best thereof: and ye shall not profane the holy things of the children of Israel, that ye die not.