Numbers 15:17-21

The LORD said to Moses, ‘Speak to the Israelites and say to them: “When you enter the land to which I am taking you and you eat the food of the land, present a portion as an offering to the LORD. Present a loaf from the first of your ground meal and present it as an offering from the threshing-floor. Throughout the generations to come you are to give this offering to the LORD from the first of your ground meal.