2 Samuel 18:2

And David, having made three divisions of his army, 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, the three divisions thus being sent forth under the command of these three tested warriors. And the king said unto the people, I will surely go forth with you myself also, in supreme command of all the forces.