2 Samuel 3:24-27

24Then Joab came to the king, and said, What hast thou done? behold, Abner came to thee; why is it [that] thou hast sent him away, and he is gone?

25Thou knowest Abner the son of Ner, that he came to deceive thee, to know thy going out and thy coming in, and to know all that thou doest.

26And when Joab was come out from David, he sent messengers after Abner, who brought him again from the well of Sirah; but David did not know it.

27And when Abner was returned to Hebron, Joab took him aside in the gate to speak with him secretly, and smote him there in the belly, that he died, for the blood of Asahel his brother.