2 Samuel 3:28-31

28When David heard about it, he declared, “I vow by the Lord that I and my kingdom are forever innocent of this crime against Abner son of Ner.

29Joab and his family are the guilty ones. May the family of Joab be cursed in every generation with a man who has open sores or leprosy or who walks on crutches or dies by the sword or begs for food!”

30So Joab and his brother Abishai killed Abner because Abner had killed their brother Asahel at the battle of Gibeon.

31Then David said to Joab and all those who were with him, “Tear your clothes and put on burlap. Mourn for Abner.” And King David himself walked behind the procession to the grave.