Deuteronomy 8:2-4

2And you shall remember the whole way that the Lord your God has led you these forty years in the wilderness, that he might humble you, testing you to know what was in your heart, whether you would keep his commandments or not.

3And he humbled you and let you hunger and fed you with manna, which you did not know, nor did your fathers know, that he might make you know that man does not live by bread alone, but man lives by every word that comes from the mouth of the Lord.

4Your clothing did not wear out on you and your foot did not swell these forty years.