22 Then said Ahimaaz the son of Zadok yet again to Joab, But howsoever,  let me, I pray thee, also run after Cushi. And Joab said, Wherefore wilt thou run, my son, seeing that thou hast no tidings ready?
22 Ahimaaz son of Zadok again said to Joab, "Come what may, please let me run behind the Cushite." But Joab replied, "My son, why do you want to go? You don't have any news that will bring you a reward."
22 Then Ahimaaz the son of Zadok said again to Joab, "Come what may, let me also run after the Cushite." And Joab said, "Why will you run, my son, seeing that you will have no reward for the news?"
22 Ahimaaz son of Zadok kept at it, begging Joab, "What does it matter? Let me run too, following the Cushite." Joab said, "Why all this 'Run, run'? You'll get no thanks for it, I can tell you."
22 And Ahimaaz the son of Zadok said again to Joab, "But whatever happens, please let me also run after the Cushite." So Joab said, "Why will you run, my son, since you have no news ready?"
22 But Ahimaaz continued to plead with Joab, "Whatever happens, please let me go, too." "Why should you go, my son?" Joab replied. "There will be no reward for your news."
Matthew Henry's Commentary on 2 Samuel 18:22
Commentary on 2 Samuel 18:19-33
(Read 2 Samuel 18:19-33)
By directing David to give God thanks for his victory, Ahimaaz prepared him for the news of his son's death. The more our hearts are fixed and enlarged, in thanksgiving to God for our mercies, the better disposed we shall be to bear with patience the afflictions mixed with them. Some think David's wish arose from concern about Absalom's everlasting state; but he rather seems to have spoken without due thought. He is to be blamed for showing so great fondness for a graceless son. Also for quarrelling with Divine justice. And for opposing the justice of the nation, which, as king, he had to administer, and which ought to be preferred before natural affection. The best men are not always in a good frame; we are apt to over-grieve for what we over-loved. But while we learn from this example to watch and pray against sinful indulgence, or neglect of our children, may we not, in David, perceive a shadow of the Saviour's love, who wept over, prayed for, and even suffered death for mankind, though vile rebels and enemies.