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. (Numbers 15:20)
This was not placed upon the altar, but was given to the priests, who were allotted all heave offerings (ch. 18:8). They were called “heave offerings” because they were lifted up in presentation to the Lord as the Creator and Giver of all good things.