2 Samuel 18:1-2

1Then David mustered the people who were with him and set commanders of thousands and captains of hundreds over them.

2Then David sent out the troops, one third under the command of Joab, one third under the command of Joab’s brother Abishai son of Zeruiah, and one third under the command of Ittai the Gittite. The king said to the troops, “I must certainly go out with you also.”