Numbers 15:19-21

15:19 and you eat some of the food of the land, you must offer up a raised offering to the Lord. 15:20 You must offer up a cake of the first of your finely ground flour as a raised offering; as you offer the raised offering of the threshing floor, so you must offer it up. 15:21 You must give to the Lord some of the first of your finely ground flour as a raised offering in your future generations.