And he said unto them, I am an hundred and twenty years old this day; I can no more go out and come in: also the Lord hath said unto me, Thou shalt not go over this Jordan. (Deuteronomy 31:2)
He evidently knew that his work was almost finished. He died soon after this (ch. 34:7). When Moses stood before Pharaoh he was 80 years old (Ex. 7:7). Since then the 40 years of the desert wanderings had passed.