2 Samuel 3:27-30

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.

28And afterwards David heard [it], and he said, I and my kingdom are guiltless before Jehovah for ever from the blood of Abner the son of Ner:

29let it fall on the head of Joab, and on all his father's house; and let there not fail from the house of Joab one that has an issue, or that is a leper, or that leans on a staff, or that falls by the sword, or that lacks bread!

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