But Joab and Abishai pursued Abner. By sunset, they had gone as far as the hill of Ammah opposite Giah on the way to the wilderness of Gibeon.
We have here the contest between Abner and Asahel. Asahel, the brother of Joab and cousin-german to David, was one of the principal commanders of David's forces, and was famous for swiftness in running: he was as light of foot as a wild roe (Sa2 2:18); this he got the name of by swift pursuing, not swift flying.
Commenting on 2 Samuel 2:18-24
Joab also and Abishai pursued after Abner,.... Or rather but Joab, &c. (n). They stood not still as the rest, but, filled with indignation and resentment, pursued after Abner, to be avenged on him: and the sun went down when they came to the hill of Ammah; a hill by the side of which was a pool of water, as Kimchi thinks, and from thence...
2Sa 2:24 But Joab and Abishai pursued Abner till the sun set, and until they had arrived at the hill Ammah, in front of Giah, on the way to the desert of Gibeon. Nothing further is known of the places mentioned here.