Clarke's Bible Commentary - 2 Samuel 18:14
Verse 14. I may not tarry thus with thee] He had nothing to say in vindication of the purpose he had formed. Thrust them through the heart of Absalom] He was determined to make sure work, and therefore he pierced his heart.
Joab should have obeyed the king's commandment: and yet the safety of the state required the sacrifice of Absalom. But independently of this, his life was quadruply forfeited to the law:-1. In having murdered his brother Amnon. 2. In having excited an insurrection in the state. 3. In having taken up arms against his own father, Deut. xxi. 18, 21. 4. In having lain with his father's concubines, Lev. xviii. 29. Long ago he should have died by the hand of justice; and now all his crimes are visited on him in his last act of rebellion. Yet, in the present circumstances, Joab's act was base and disloyal, and a cowardly murder.
John Gill's Bible Commentary
Ver. 14. Then said Joab, I may not tarry thus with thee , etc.] It is not worth while to talk with thee any longer, nor must I lose time, and neglect my opportunity; I do not desire you to go and smite him, I will go and do it myself: and he took three darts in his hand ; or three rods, which were either all iron, or however the tops of them were iron spikes: and thrust them through the heart of Absalom ; or through the midst of his body; for if he had thrust through his heart, properly speaking, he must have died instantly, whereas he seems to have lived after this: while he [was] yet alive ; Joab found him alive when he came to him, and so he was when he thrust his darts through him; and so he was afterward; for the words may be rendered, “being yet alive”, even after the darts were fixed in him, and even so deeply as to pierce through his body: in the midst , or “heart”, of the oak ; into which the darts penetrated.
Matthew Henry Commentary
Verses 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 abhorrenc of rebellion against parents. Nothing can preserve men from misery an contempt, but heavenly wisdom and the grace of God.
Original Hebrew
ויאמר 559 יואב 3097 לא 3808 כן 3651 אחילה 3176 לפניך 6440 ויקח 3947 שׁלשׁה 7969 שׁבטים 7626 בכפו 3709 ויתקעם 8628 בלב 3820 אבשׁלום 53 עודנו 5750 חי 2416 בלב 3820 האלה׃ 424