Exodus 16:14-16
When the dew was gone, thin flakes like frost on the ground appeared on the desert floor.
When the Israelites saw it, they said to each other, "What is it?" For they did not know what it was.
Moses said to them, "It is the bread the LORD has given you to eat.
This is what the LORD has commanded: 'Each one is to gather as much as he needs. Take an omer for each person you have in your tent.' "