Deuteronomy 31:2-6

And he said unto them, I am a hundred and twenty years old this day; I can no more go out and come in: and Jehovah hath said unto me, Thou shalt not go over this Jordan. Jehovah thy God, he will go over before thee; he will destroy these nations from before thee, and thou shalt dispossess them: and Joshua, he shall go over before thee, as Jehovah hath spoken. And Jehovah will do unto them as he did to Sihon and to Og, the kings of the Amorites, and unto their land; whom he destroyed. And Jehovah will deliver them up before you, and ye shall do unto them according unto all the commandment which I have commanded you. Be strong and of good courage, fear not, nor be affrighted at them: for Jehovah thy God, he it is that doth go with thee; he will not fail thee, nor forsake thee.