פּירוש אויף דברים 31:5

אשר צויתי אתכם, “which I have commanded you.” This is a reference to Deut. 20,16, where G-d had commanded the Jewish people not to allow a single soul of the Canaanites to remain alive, (unless they had left that land of their own accord).

and you will deal with them i.e., to destroy their altars.