Joab was a son of Zeruiah, King David’s sister (1 Chronicles 2:13–17) and was therefore one of David’s nephews. Joab’s brothers were two of David’s brave warriors, Abishai and Asahel. Joab was positioned as commander of David’s armies because of his victory over the Jebusites, resulting in the possession of the city of Jerusalem. It was through this victory that Jerusalem became “the city of David” (1 Chronicles 11:4–9).
Joab fought and won many battles for the king, but his personal lack of self-control was problematic. In a war against the forces of Ish-Bosheth, Joab’s brother Asahel was killed by Abner, the commander of Ish-Bosheth’s armies. Joab was furious and pursued Abner to kill him, but Abner escaped (2 Samuel 2:12–32). Later, after Abner swore allegiance to David, Joab’s fuse blew, and his desire to avenge his brother’s blood drove him to deceive and murder Abner (verses 26–27). This action deeply grieved David, but the king felt unable to bring justice against the mighty Joab (verse 39). Instead, David pronounced a curse over Joab and his future descendants: “May his blood fall on the head of Joab and on his whole family! May Joab’s family never be without someone who has a running sore or leprosy or who leans on a crutch or who falls by the sword or who lacks food” (verse 29).
As the commander of David’s armies, Joab was provided many victories by God, but Joab caused much grief to the king and to Israel. His anger and perhaps the power of his position drove him to poor decisions at times. In addition to his murder of Abner, Joab killed his own cousin, Amasa—and his betrayal was Judas-style, accompanied by a kiss: “Joab said to Amasa, ‘How are you, my brother?’ Then Joab took Amasa by the beard with his right hand to kiss him. Amasa was not on his guard against the dagger in Joab’s hand, and Joab plunged it into his belly, and his intestines spilled out on the ground. Without being stabbed again, Amasa died” (2 Samuel 20:9–10). Joab disobeyed King David’s command to spare Absalom’s life, himself striking Absalom with three javelins (2 Samuel 18). David mourned the death of his son Absalom, a response that was sternly reprimanded by Joab (2 Samuel 19:1–8). It was also Joab who, in accordance with David’s command, placed Uriah the Hittite at the front of the battle to be killed, so that David could feel justified in marrying Uriah’s widow (2 Samuel 11).
Joab, for all his faults, was obviously a capable man of war and valiant on the battlefield. And he ought to be given credit for his loyalty to David for almost four decades. Joab also counseled David when David sinfully desired to take a census; if David had heeded Joab’s advice, he could have spared his nation the plague that befell Israel (2 Samuel 24).
When David was on his death bed, Joab conspired with Adonijah to install Adonijah as the next king, instead of Solomon (1 Kings 1). This action, plus Joab’s other rash decisions, vengeful murders, and inability to take certain important orders, finally drove David over the edge. David commanded Solomon to ensure Joab’s execution, an act that was carried out by Benaniah as Joab was clinging to the horns of the altar in hopes of finding clemency (1 Kings 2:5–6, 28–34).