Deuteronomy 31:2-6

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. The LORD thy God, he will go over before thee, and he will destroy these nations from before thee, and thou shalt possess them: and Joshua, he shall go over before thee, as the LORD hath said. And the LORD shall do unto them as he did to Sihon and to Og, kings of the Amorites, and unto the land of them, whom he destroyed. And the LORD shall give them up before your face, that ye may do unto them according unto all the commandments which I have commanded you. Be strong and of a good courage, fear not, nor be afraid of them: for the LORD thy God, he it is that doth go with thee; he will not fail thee, nor forsake thee.