וּנְתָנָ֥ם יְהוָ֖ה לִפְנֵיכֶ֑ם וַעֲשִׂיתֶ֣ם לָהֶ֔ם כְּכָל־הַמִּצְוָ֔ה אֲשֶׁ֥ר צִוִּ֖יתִי אֶתְכֶֽם׃
And the LORD will deliver them up before you, and ye shall do unto them according unto all the commandment which I have commanded you.
Chizkuni
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).