All Israel, i.e. the elders and chieftains of all Israel, representing and ruling all the rest.
Related Commentaries of 2 Samuel 3:21
2 Samuel 3:21
21 And Abner said unto David, I will arise and go, and will gather all Israel unto my lord the king, that they may make a league with thee, and that thou mayest reign over all that thine heart desireth. And David sent Abner away; and he went in peace.