Then Abishai [David’s nephew], the son of Zeruiah, said to the king, “Why should this dead dog (despicable person) curse my lord the king? Let me go over and take off his head.”

And when they were come to the great stone in Gibeon, Amasa met them. And Joab had his garment that he had about him, gird unto him, and had girded thereon a knife joined fast to his loins, in such a sheath that as he went it fell sometimes out.

Amasa did not protect himself from the knife in Joab's other hand, and Joab stabbed him in the abdomen, causing Amasa's intestines to spill out on the ground. There was no need to stab him again; the first blow was fatal. Then Joab and his brother Abishai pursued Sheba son of Bicri.