Neither side had the advantage in the combat of twelve a side; hence, the quarrel was fought out with great fierceness by the two armies, and the victory was won by David.
Matthew Henry
Concise Bible Commentary
The nation in general refused David. By this the Lord trained up his servant for future honour and usefulness; and the tendency of true godliness was shown in his behaviour while passing through various difficulties. David was herein a type of Christ, whom Israel would not submit to, though anointed of the Father to be a Prince and a Saviour to them. Abner meant, Let the young men fight before us, when he said, Let them play before us: fools thus make a mock at sin. But he is unworthy the name of a man, that can thus trifle with human blood.
SDA Bible Commentary (limited)
Volume 1-7
17. A very sore battle. The numbers engaged were probably not large, since the total of those slain was only 20 on the side of David and 360 on the side of Israel (vs.30, 31), but the contest was fought out with a fierceness that brought a decisive victory to the forces of Judah.