John Wesley on 2 Chronicles 21:17

His wives - Whom also they slew, chap.22:1, except Ahaziah and Athaliah; who possibly were hidden in some secret place. Left him - Blood for blood. He had slain all his brethren; they slay all his sons, but one. And he had not escaped, had be not been of the house of David; which must not be extirpated, like that of Ahab: because a blessing was in it; no less a blessing than that of the Messiah.