2 Samuel 18:2, 14-15

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.

Then said Joab, I may not tarry thus with thee. And he took three darts in his hand, and thrust them through the heart of Absalom, while he was yet alive in the midst of the oak. And ten young men that bare Joab's armour compassed about and smote Absalom, and slew him.