Numbers 15:17-21

Then the LORD spoke to Moses, saying, “Speak to the Israelites and say to them, ‘When you enter the land to which I am bringing you, then, when you eat the food of the land, you shall lift up an offering (heave offering) to the LORD. You shall lift up a cake made of the first of your [ground grain which has been made into] dough as an offering [to the Lord]; as an offering from the threshing floor, so shall you lift it up. From the first of your dough (ground grain) you shall give to the LORD an offering throughout your generations.