Adam Clarke on Exodus 34:10

I will do marvels - This seems to refer to what God did in putting them in possession of the land of Canaan, causing the walls of Jericho to fall down; making the sun and moon to stand still, etc. And thus God made his covenant with them; binding himself to put them in possession of the promised land, and binding them to observe the precepts laid down in the following verses, from Exodus 34:11-26 inclusive.