Exodus 16:32-33

32Then Moses said, “This is the thing which the Lord has commanded: ‘Fill an omer with it, to be kept for your generations, that they may see the bread with which I fed you in the wilderness, when I brought you out of the land of Egypt.’ ”

33And Moses said to Aaron, “Take a pot and put an omer of manna in it, and lay it up before the Lord, to be kept for your generations.”