Deuteronomy 20:16-18

16But a  in the cities of these peoples that the  Lord your God is giving you for an inheritance, you shall save alive nothing that breathes, 17but b  you shall devote them to complete destruction
That is, set apart ( devote) as an offering to the Lord (for destruction)
the Hittites and the Amorites, the Canaanites and the Perizzites, the Hivites and the Jebusites, as the  Lord your God has commanded,
18that d  they may not teach you to do according to all their abominable practices that they have done for their gods, and so you e  sin against the  Lord your God.

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