Joab then left David and sent messengers after Abner, and they brought him back from the cistern at Sirah. But David did not know it.
Now when Abner returned to Hebron, Joab took him aside into an inner chamber, as if to speak with him privately. And there, to avenge the blood of his brother Asahel, Joab stabbed him in the stomach, and he died.
Later, when David heard about this, he said, “I and my kingdom are forever innocent before the LORD concerning the blood of Abner son of Ner.
May his blood fall on the head of Joab and on his whole family! May Joab’s family never be without someone who has a running sore or leprosy or who leans on a crutch or who falls by the sword or who lacks food.”
(Joab and his brother Abishai murdered Abner because he had killed their brother Asahel in the battle at Gibeon.)