John Wesley on 2 Samuel 4:4

Jonathan had a son - This history is inserted as that which encouraged these men to this wicked murder, because Saul's family was now reduced to a low ebb; and if Isbosheth was dispatched, there would be none left, but a lame child, who was altogether unfit to manage the kingdom, and therefore the crown must necessarily come to David by their act and deed; for which they promised themselves no small recompense. Jezreel - The place of that last and fatal fight.