When Joab saw the battle lines before him and behind him, he selected some of the best men of Israel and arrayed them against the Arameans.
Here we have, I. The preparation which the Ammonites made for war, Sa2 10:6. They saw they had made themselves very odious to David and obnoxious to his just displeasure. This they might easily have foreseen when they abused his ambassadors, which was no other than a challenge to war, and a bold defiance of him.
Commenting on 2 Samuel 10:6-14
When Joab saw that the front of the battle was against him before and behind,.... Or "the face" of it (w); armies appeared both before and behind, about to attack him both in front and rear; the Targum is,"and Joab saw that the warriors, or those that made war, were strong against him before and behind:" he chose of all the choice men of Israel...
Before and behind - It is probable that one of the armies was in the field, and the other in the city, when Joab arrived. When he fronted this army, the other appears to have issued from the city, and to have taken him in the rear; he was therefore obliged to divide his army as here mentioned; one part to face the Syrians commanded...