Deuteronomy 8:2-3

And thou shalt remember all the way through which the Lord thy God hath brought thee for forty years through the desert, to afflict thee and to prove thee, and that the things that were known in thy heart might be made known, whether thou wouldst keep his commandments or no.

He afflicted thee with want, and gave thee manna for thy food, which neither thou nor thy fathers knew: to shew that not in bread alone doth man live, but in every word that proceedeth from the mouth of God.