Numbers 15:17-21

And the LORD spake unto Moses, saying, Speak unto the children of Israel, and say unto them, When ye come into the land whither I bring you, then it shall be, that, when ye eat of the bread of the land, ye shall offer up an heave offering unto the LORD. Ye shall offer up a cake of the first of your dough for an heave offering: as ye do the heave offering of the threshingfloor, so shall ye heave it. Of the first of your dough ye shall give unto the LORD an heave offering in your generations.