5 The king commanded Joab and Abishai and Ittai, saying, “Deal gently for my sake with the young man, even with Absalom.” All the people heard when the king commanded all the captains concerning Absalom. 6 So the people went out into the field against Israel: and the battle was in the forest of Ephraim. 7 The people of Israel were struck there before the servants of David, and there was a great slaughter there that day of twenty thousand men. 8 For the battle was there spread over the surface of all the country; and the forest devoured more people that day than the sword devoured.
9 Absalom happened to meet the servants of David. Absalom was riding on his mule, and the mule went under the thick boughs of a great oak, and his head caught hold of the oak, and he was taken up between the sky and earth; and the mule that was under him went on. 10 A certain man saw it, and told Joab, and said, “Behold, I saw Absalom hanging in an oak.” 11 Joab said to the man who told him, “Behold, you saw it, and why didn’t you strike him there to the ground? I would have given you ten pieces of silver, and a sash.” 12 The man said to Joab, “Though I should receive a thousand pieces of silver in my hand, I still wouldn’t put forth my hand against the king’s son; for in our hearing the king commanded you and Abishai and Ittai, saying, ‘Beware that none touch the young man Absalom.’ 13 Otherwise if I had dealt falsely against his life (and there is no matter hidden from the king), then you yourself would have set yourself against me.” 14 Then Joab said, “I’n not going to wait like this with you.” 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. 15 Ten young men who bore Joab’s armor surrounded and struck Absalom, and killed him.
Matthew Henry's Commentary on 2 Samuel 18:5-15
Commentary on 2 Samuel 18:1-8
(Read 2 Samuel 18:1-8)
How does David render good for evil! Absalom would have only David smitten; David would have only Absalom spared. This seems to be a resemblance of man's wickedness towards God, and God's mercy to man, of which it is hard to say which is most amazing. Now the Israelites see what it is to take counsel against the Lord and his anointed.
Commentary on 2 Samuel 18:9-18
(Read 2 Samuel 18:9-18)
Let young people look upon Absalom, hanging on a tree, accursed, forsaken of heaven and earth; there let them read the Lord's abhorrence of rebellion against parents. Nothing can preserve men from misery and contempt, but heavenly wisdom and the grace of God.