However, in the cities of the nations that the LORD your God is giving you as an inheritance, you must not leave alive anything that breathes.
They are here directed what method to take in dealing with the cities (these only are mentioned, Deu 20:10, but doubtless the armies in the field, and the nations they had occasion to deal with, are likewise intended) upon which they made war.
Commenting on Deuteronomy 20:10-20
But of the cities of those people, which the Lord thy God doth give thee for an inheritance,.... The cities of the seven nations, six of which are mentioned by name in the next verse: thou shalt save alive nothing that breatheth; the reason of this severity was because of their wickedness, the capital crimes and gross abominations they were guilty of, and for which...
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.
Commenting on Deuteronomy 20:15-18