Deuteronomy 8:2-6

And thou shalt remember all the way which Jehovah thy God hath led thee these forty years in the wilderness, that he might humble thee, to prove thee, to know what was in thy heart, whether thou wouldest keep his commandments, or not. 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 everything that proceedeth out of the mouth of Jehovah doth man live. Thy raiment waxed not old upon thee, neither did thy foot swell, these forty years. And thou shalt consider in thy heart, that, as a man chasteneth his son, so Jehovah thy God chasteneth thee. And thou shalt keep the commandments of Jehovah thy God, to walk in his ways, and to fear him.