A pattern emerges from Exodus where the Israelites grumble and complain against God. But we find that the Israelites problem is not simply that they are so needy and faithless, but that they are truly needy enough. 

"Then the Lord said to Moses, 'Behold, I am about to rain bread from heaven for you, and the people shall go out and gather a day's portion every day, that I may test them, whether they will walk in my law or not.'" Exodus 16:4