2 Samuel 3:24-27

24Then Joab came to the king and said, “What have you done? Behold, Abner came to you; why then have you let him go, so that he is already gone? 25You know Abner the son of Ner, that he came to gain your confidence, and to learn of 1your 2going out and coming in and to find out everything that you are doing.”

26When Joab left David’s presence, he sent messengers after Abner, and they brought him back from the well of Sirah; but David did not know about it. 27So when Abner returned to Hebron, Joab took him aside into the middle of the gate to speak with him privately, and there 3he struck him in the belly, so that he died on account of the blood of his brother Asahel.