Sforno on Deuteronomy 7:24/ספורנו על דברים ז׳:כ״ד

1ונתן מלכיהם בידך והאבדת את שמם, for allowing any of these Canaanites to survive would become an ongoing source of irritation for you, as demonstrated by the young Haddad, sole survivor of the people of Edom, who became a lifelong source of irritation (militarily) for such a powerful king as Solomon. (Kings I 11,14 and onwards)