"He left no one remaining… as the LORD, the God of Israel, commanded" (10:40). Where does that command come from?

10:40 ties the whole southern campaign to a command: "He left no one remaining, but he utterly destroyed all that breathed, as the LORD, the God of Israel, commanded" (tap breathed). Moses had given it for "the cities of these peoples that the LORD your God gives you for an inheritance": "you shall save alive nothing that breathes; but you shall utterly destroy them: the Hittite, the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite, as the LORD your God has commanded you" (Deuteronomy 20:16-17). In Hebrew, 10:40's all that breathed and Deuteronomy's nothing that breathes are both kol (all) with neshamah (breath). The five kings were "the five kings of the Amorites" (10:5), one of the peoples named there. Chapter 6's honest question sets out the main ways Christians read this command (6:21), each view on its verses, and it isn't repeated here. This chapter sets one thing beside it: the war began when Joshua went up to save Gibeon (10:6-7). The Gibeonites were Hivites (9:7), another of the peoples Deuteronomy 20:17 names, and Israel had made a covenant "to let them live" (9:15); chapter 9 tells how. The book later says, "There was not a city that made peace with the children of Israel, except the Hivites, the inhabitants of Gibeon" (11:19).