Then Joab came to the king, and said, What hast thou done? behold, Abner came unto thee; why [is] it [that] thou hast sent him away, and he is quite gone? (3:24)

Thou knowest Abner the son of Ner, that he came to deceive thee, and to know thy going out and thy coming in, and to know all that thou doest. (3:25)

And when Joab was come out from David, he sent messengers after Abner, which brought him again from the well of Sirah: but David knew [it] not. (3:26)

And when Abner was returned to Hebron, Joab took him aside in the gate to speak with him quietly, and smote him there under the fifth [rib], that he died, for the blood of Asahel his brother. (3:27)

And Joab said to Amasa, [Art] thou in health, my brother? And Joab took Amasa by the beard with the right hand to kiss him. (20:9)

But Amasa took no heed to the sword that [was] in Joab's hand: so he smote him therewith in the fifth [rib], and shed out his bowels to the ground, and struck him not again; and he died. So Joab and Abishai his brother pursued after Sheba the son of Bichri. (20:10)

--1 Kings--

Moreover thou knowest also what Joab the son of Zeruiah did to me, [and] what he did to the two captains of the hosts of Israel, unto Abner the son of Ner, and unto Amasa the son of Jether, whom he slew, and shed the blood of war in peace, and put the blood of war upon his girdle that [was] about his loins, and in his shoes that [were] on his feet. (2:5)