2 Samuel 18:1-2

1And David numbered the people who were with him, and set captains of thousands and captains of hundreds over them.

2Then David sent out one third of the people under the hand of Joab, one third under the hand of Abishai the son of Zeruiah, Joab’s brother, and one third under the hand of Ittai the Gittite. And the king said to the people, “I also will surely go out with you myself.”