At this point in time, the people outside of Judah have probably not been told about what David did following the death of Abner. As a result, they thought that what had been done to Abner would be done to them.1They thought that David would take vengeance on those who were loyal to Saul and refused to support him after Saul’s death.2
1 When Ish-bosheth, Saul’s son, heard that Abner had died at Hebron, his courage failed, and all Israel was dismayed.