Abner and David

In chapter 3, of the book 2 Samuel, we start with severe fighting between David's people and the late Saul's.

Meet Abner, one of Saul's most loyal followers.  He leads the crusade against David until he is accused of sleeping with Saul's concubine by Ishboseth.  Abner becomes upset and completely betrayed by this false accusation, and comes to an agreement with David to join forces.

When Abner heads back to convince the rest of Saul's people to join forces with David, he meets up with Joab, one of David's officials.  When no one is looking, Joab stabs Abner in the stomach, murdering him--he did this because Abner killed Joab's brother in a previous battle.

David is enraged by this.  He mourned heavily for Abner's death, which impressed Saul's peope.