Exodus 16:4, 8

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).

Moses said, “This will happen when the LORD gives you meat to eat in the evening, and in the morning [enough] bread to be fully satisfied, because the LORD has heard your murmurings against Him; for what are we? Your murmurings are not against us, but against the LORD.”