Here is where God tells how there will be an Angel with them, and how he will drive the foreign people out as they progress.
He won't do it all at once, because the land will lay waste before they get to it. He tells the Israelites not to make any agreements with the people or worship their gods.
Then he calls Moses up the mountain.
Ya get that?????????? He told them what He was going to do and how He was going to do it!