Exodus 16:4-5

Then the LORD said to Moses, “Behold, I will cause bread to rain from heaven for you; the people shall go out and gather a day’s portion every day, so that I may test them [to determine] whether or not they will walk [obediently] in My instruction (law). And it shall be that on the sixth day, they shall prepare to bring in twice as much as they gather daily [so that they will not need to gather on the seventh day].”