Deuteronomy 8:2-4

2You are to remember all the way that Adonai your God has led you these 40 years in the wilderness—in order to humble you, to test you, to know what was in your heart, whether you would keep His mitzvot or not.

3He afflicted you and let you hunger, then He fed you manna —which neither you nor your fathers had known—in order to make you understand that man does not live by bread alone but by every word that comes from the mouth of Adonai.

4Neither did your clothing wear out on you, nor did your foot swell these 40 years.