Under the hand of Joab, to wit, for his especial conduct and management in the battle: otherwise Joab was the general of all the forces; nor had David yet taken away that power from him, nor was this a time to do it. But such distributions of forces are usual in battles. I will surely go forth with you myself also, that by my presence I may put life and courage into my soldiers; and because it is fit I should run the same hazards with you, which you do for my sake.
Related Commentaries of 2 Samuel 18:2
2 Samuel 18:2
2 And David sent forth a third part of the people under the hand of Joab, and a third part under the hand of Abishai the son of Zeruiah, Joab's brother, and a third part under the hand of Ittai the Gittite. And the king said unto the people, I will surely go forth with you myself also.