Numbers 18:27-28

²⁷And your heave-offering shall be reckoned unto you, like the corn of the threshing-floor, and as the fulness of the wine-press.

²⁸Thus shall ye also offer a heave-offering unto the Lord from all your tithes, which ye may receive from the children of Israel; and ye shall give thereof the heave-offering of the Lord to Aaron the priest.