21 Then Joab said to the Cushite, "Go, tell the king what you have seen." So the Cushite bowed himself to Joab and ran. 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?" 23 "But whatever happens," he said, "let me run." So he said to him, "Run." Then Ahimaaz ran by way of the plain, and outran the Cushite. 24 Now David was sitting between the two gates. And the watchman went up to the roof over the gate, to the wall, lifted his eyes and looked, and there was a man, running alone. 25 Then the watchman cried out and told the king. And the king said, "If he is alone, there is news in his mouth." And he came rapidly and drew near.
Matthew Henry's Commentary on 2 Samuel 18:21-25
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.