Who was Abner?
Abner was the captain of the host under Saul and Ishbosheth (Eshbaal). He was Saul's cousin; Ner the father of Abner and Kish the father of Saul being brothers, the sons of Abiel (1 Samuel 14:50 ). In 1 Chronicles 8:33 ; 1 Chronicles 9:39 the text appears to be faulty; read: And Ner begat Abner, and Kish begat Saul. According to 1 Chronicles 27:21 Abner had a son by the name of Jaasiel.
Abner was to Saul what Joab was to David. Despite the many wars waged by Saul, we hear little of Abner during Saul's lifetime. Not even in the account' of the battle of Gilboa is mention made of him. Yet both his high office and his kinship to the king must have brought the two men in close contact. On festive occasions it was the custom of Abner to sit at table by the king's side (1 Samuel 20:25 ). It was Abner who introduced the young David fresh from his triumph over Goliath to the king's court (so according to the account in 1 Samuel 17:57 ). We find Abner accompanying the king in his pursuit of David (1 Samuel 26:5 ).
Abner is rebuked by David for his negligence in keeping watch over his master (ibid., 15). Upon the death of Saul, Abner took up the cause of the young heir to the throne, Ishbosheth, whom he forthwith removed from the neighborhood of David to Mahanaim in the East-Jordanic country. There he proclaimed him king over all Israel. By the pool of Gibeon he and his men met Joab and the servants of David. Twelve men on each side engaged in combat which ended disastrously for Abner who fled. He was pursued by Asahel, Joab's brother, whom Abner slew. Though Joab and his brother Abishai sought to avenge their brother's death on the spot, a truce was effected; Abner was permitted to go his way after three hundred and threescore of his men had fallen.
Joab naturally watched his opportunity. Abner and his master soon had a quarrel over Saul's concubine, Rizpah, with whom Abner was intimate. It was certainly an act of treason which Ishbosheth was bound to resent. The disgruntled general made overtures to David; he won over the tribe of Benjamin. With twenty men of them he came to Hebron and arranged with the king of Judah that he would bring over to his side all Israel. He was scarcely gone when Joab learned of the affair; without the knowledge of David he recalled him to Hebron where he slew him, "for the blood of Asahel his brother."
David mourned sincerely the death of Abner. "Know ye not," he addressed his servants, "that there is a prince and a great man fallen this day in Israel?" He followed the bier in person. Of the royal lament over Abner a fragment is quoted: "Should Abner die as a fool dieth? Thy hands were not bound, nor thy feet put into fetters: As a man falleth before the children of iniquity, so didst thou fall." (See 2 Sam 3:6-38.) The death of Abner, while it thus cannot in any wise be laid at the door of David, nevertheless served his purposes well. The backbone of the opposition to David was broken, and he was soon proclaimed as king by all Israel.
IBSE, "Abner" (in the public domain) with minor edits.