Deuteronomy 8:2-3

Remember that these forty years the LORD your God led you all the way in the wilderness, so that He might humble you and test you in order to know what was in your heart, whether or not you would keep His commandments.

He humbled you, and in your hunger He gave you manna to eat, which neither you nor your fathers had known, so that you might understand that man does not live on bread alone, but on every word that comes from the mouth of the LORD.