Deuteronomy 8:2-6

And thou shalt remember all the way which the LORD thy God led thee these forty years in the wilderness, to humble thee, and to prove thee, to know what was in thine heart, whether thou wouldest keep his commandments, or no. And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the LORD doth man live. Thy raiment waxed not old upon thee, neither did thy foot swell, these forty years. Thou shalt also consider in thine heart, that, as a man chasteneth his son, so the LORD thy God chasteneth thee. Therefore thou shalt keep the commandments of the LORD thy God, to walk in his ways, and to fear him.