Deuteronomy 8:2-5

2And you shall remember that the Lord your God led you all the way these forty years in the wilderness, to humble you and test you, to know what was in your heart, whether you would keep His commandments or not.

3So He humbled you, allowed you to hunger, and fed you with manna which you did not know nor did your fathers know, that He might make you know that man shall not live by bread alone; but man lives by every word that proceeds from the mouth of the Lord.

4Your garments did not wear out on you, nor did your foot swell these forty years.

5You should know in your heart that as a man chastens his son, so the Lord your God chastens you.