2 Samuel 3:26-30 - Joab Murders Abner
26 As soon as Joab left David, Joab sent messengers after Abner, and they brought him back from the cistern at Sirah, but David was not aware of this. 27 When Abner returned to Hebron, Joab brought him aside within the gateway to talk to him alone and then stabbed him in the abdomen. So he died for shedding the blood of Joab's brother Asahel.
28 Later on, David found out about it and proclaimed, "Let me and my kingdom remain guiltless forever in the LORD's presence for the death of Ner's son Abner. 29 May judgment rest on Joab's head and on his father's entire household. May Joab's dynasty never be without one who has a discharge, who is a leper, who walks with a cane, who commits suicide, or who lacks food!" 30 He said this because Joab and his brother Abishai murdered Abner after he had killed their brother Asahel in the battle at Gibeon.