Exodus 16:33-37

And Moses said to Aaron, “Take a jar and put a full omer of manna in it, and place it before the Lord to be kept safe throughout your generations.”

As the Lord commanded Moses, so Aaron placed it before the Testimony, to be kept.

And the sons of Israel ate the manna for forty years, until they came to an inhabited land; they ate the manna until they came to the border of the land of Canaan.

(Now an omer is a tenth of an ephah.)