Exodus 16:18, 33, 36

And when they measured it by the omer, the one who gathered much did not have too much, and the one who gathered little did not have too little. Everyone had gathered just as much as they needed.

So Moses said to Aaron, “Take a jar and put an omer of manna in it. Then place it before the LORD to be kept for the generations to come.”

(An omer is one-tenth of an ephah.)