2 Samuel 3:27-30

27When Abner returned to Hebron, Joab took him aside at the gate as if to speak privately with him. Joab then stabbed him in the abdomen and killed him, avenging the shed blood of his brother Asahel.

28When David later heard about this, he said, “I and my kingdom are forever innocent before the Lord of the shed blood of Abner son of Ner!

29May his blood whirl over the head of Joab and the entire house of his father! May the males of Joab’s house never cease to have someone with a running sore or a skin disease or one who works at the spindle or one who falls by the sword or one who lacks food!”

30So Joab and his brother Abishai killed Abner, because he had killed their brother Asahel in Gibeon during the battle.