Deuteronomy 11:2

And know ye this day, think it over carefully, in order to understand it properly; for I speak not with your children which have not known, and which have not seen the chastisement of the Lord, your God, the many vicissitudes of the wilderness journey, whose purpose was to instruct, educate, the people in the duties toward God, His greatness, His mighty hand, and His stretched-out arm. Those of the people who had been less than twenty years old when the host reached Kadesh for the first time, and therefore were now between forty and sixty years old, are here addressed; for them the wilderness journey had been a school and a training.