Numbers 15:17-21

Then the LORD said to Moses, “Give the following instructions to the people of Israel. “When you arrive in the land where I am taking you, and you eat the crops that grow there, you must set some aside as a sacred offering to the LORD. Present a cake from the first of the flour you grind, and set it aside as a sacred offering, as you do with the first grain from the threshing floor. Throughout the generations to come, you are to present a sacred offering to the LORD each year from the first of your ground flour.