Faced with a sudden and powerful rebellion led by his own son, David makes a rapid strategic decision to abandon his capital, Jerusalem. This choice is driven by a clear understanding of the military reality and a deep desire to protect both his loyal followers and the city's residents. He recognizes that remaining in the capital will leave them with no chance of escape and no survivors [מצודת ציון, ביאור שטיינזלץ]. The primary approach among commentators is that staying within the city's fortress is simply impossible. Absalom is approaching with a massive, battle-ready army, while David is uncertain about who among his own inner circle remains truly loyal [מצודת דוד, מלבי״ם]. If David chooses to stay, Absalom will inevitably invade Jerusalem to capture him, ensuring their total destruction [רד״ק].
David's extreme urgency to leave is meant to prevent Absalom from overtaking them while they are still inside or even near the city. The looming threat they face is understood as a forceful, overwhelming disaster [מצודת ציון, רלב״ג, ביאור שטיינזלץ]. Some interpret this impending ruin as being so absolute that it resembles a cup being completely rinsed out, leaving absolutely nothing behind. There is even a danger that Absalom might condemn Jerusalem to the total destruction reserved for an idolatrous city [רד״ק].
The greatest fear for David is that if his group is caught near the walls, Absalom will unleash his fury upon the residents and put the city to the sword. David knows he lacks the strength to defend the city against his son's forces [ביאור שטיינזלץ]. Furthermore, if a battle erupts near the walls, Absalom's men might slaughter the residents and then falsely accuse David's men of the massacre, claiming the townspeople had rebelled against David. Alternatively, Absalom's forces might justify killing the residents by arguing that David's men were using the city as a human shield [מלבי״ם].
Another perspective views the danger to the city through Absalom's own tactical lens. If the battle takes place near Jerusalem, Absalom might worry that the city's residents will join forces with David, creating a two-front war from both inside and outside the walls. Absalom is entirely confident in his ultimate victory over his father, relying on the divine prophecy that God would bring disaster upon David from within His own household. Because of this confidence, Absalom might choose to delay his direct confrontation with David, turning his attention first to striking the city to eliminate any potential threat it poses [אלשיך]. Given all these severe risks, the only viable solution to save Jerusalem and its people is for David and his men to distance themselves as quickly as possible.