Deuteronomy 31:3-5

3But the Lord your God himself will go across the river in front of you. He will destroy the nations who live in that land. Then you will live there instead of them. Joshua will lead you across the river, as the Lord has said.

4The Lord will do to those nations the same things that he did to Sihon and to Og, the Amorite kings. He destroyed them and their land.

5The Lord will give you power over them. Then you must do to them everything that I have told you to do.