And the LORD  shall return   his blood  upon his own head, who fell   upon two  men  more righteous  and better  than he, and slew   them with the sword, my father  David  not knowing   thereof, to wit, Abner  the son  of Ner, captain  of the host  of Israel, and Amasa  the son  of Jether, captain  of the host  of Judah.