C. F. Keil and Franz Delitzsch on Deuteronomy 20:15-18

Deu 20:15-18

It was in this way that Israel was to act with towns that were far off; but not with the towns of the Canaanites (“these nations”), which Jehovah gave them for an inheritance. In these no soul was to be left alive; but these nations were to be laid under the ban, i.e., altogether exterminated, that they might not teach the Israelites their abominations and sins (cf. Deu 7:1-4; Deu 12:31). כּל־נשׁמה, lit., every breath, i.e., everything living, by which, however, human beings alone are to be understood (comp. Jos 10:40; Jos 11:11, with Deu 11:14).