Numbers 18:27-28

²⁷And 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.

²⁸Thus 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.