Deuteronomy 7:16

And thou shalt consume all the people which the Lord, thy God, shall deliver thee, giving them into the hands of Israel; thine eye shall have no pity upon them, all false sympathy, which might enter the heart through the eye as it witnesses the plight of the enemy must be banished; neither shalt thou serve their gods, for that will be a snare unto thee, which would plunge them, too, into destruction.