Numbers 15:17-21

The LORD spoke to Moses, saying, “Speak to the people of Israel and say to them, When you come into the land to which I bring you and when you eat of the bread of the land, you shall present a contribution to the LORD. Of the first of your dough you shall present a loaf as a contribution; like a contribution from the threshing floor, so shall you present it. Some of the first of your dough you shall give to the LORD as a contribution throughout your generations.