Numbers 15:17-21

17Then the Lord spoke to Moses, saying,

18“Speak to the Israelites and say to them, ‘When you enter the land to which I am bringing you,

19then, when you eat the food of the land, you shall lift up an offering (heave offering) to the Lord.

20You 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.

21From the first of your dough (ground grain) you shall give to the Lord an offering throughout your generations.