C. F. Keil and Franz Delitzsch on 2 Samuel 15:13-14

2Sa 15:13-14 David’s flight from Jerusalem. - 2Sa 15:13, 2Sa 15:14. When this intelligence reached David, “The heart of the men of Israel is after Absalom” (אהר היה, as in 2Sa 2:10, to be attached to a person as king; see at 1Sa 12:14), he said to his servants that were with him in Jerusalem, “Arise, let us flee, for there will be no escape for us from Absalom! Make speed to depart, lest he overtake us suddenly, and drive the calamity (the judgment threatened in 2Sa 12:10-11) over us, and smite the city with the edge of the sword.” David was perhaps afraid that Jerusalem might fall into Absalom’s power through treachery, and therefore resolved to fly as speedily as possible, not only in order to prevent a terrible massacre, but also to give his own faithful adherents time to assemble.