Ahimaaz was a well-known runner 2 Samuel 18:27. Speed was a heroic virtue in those simple times (compare 2 Samuel 2:18). In Hezekiah's reign 2 Chronicles 30:6, 2 Chronicles 30:10 we find an establishment of running post-men; and the same name ("runners") is given Esther 3:13 to the Persian posts, though at that time they rode on mules and camels.

Bear tidings - The original word is used almost exclusively of bearing good tidings, and hence, is rendered in the Septuagint (though not always) εὐαγγίζεσθαι euangelizesthai 2 Samuel 4:10; 1 Samuel 31:9. In 2 Samuel 18:21, it is not "carry the good tidings," but "tell," simply "announce."

Then said Ahimaaz the son of Zadok,.... To Joab; for it seems he stayed with the army when he with Jonathan brought the message from Hushai to David:

let me now run, and bear the king tidings how that the Lord hath avenged him on his enemies; which he thought would be very acceptable to hear of as soon as possible; and to be a messenger with tidings of a victory, as it was honourable, so likewise profitable then as now; though perhaps Ahimaaz might have no respect to the reward, as indeed none could be expected, since the death of Absalom would be so disagreeable to the king; but was desirous of it, that the king might be acquainted with the event of the battle as soon as might be.

David is informed of the victory, and of the death of Absalom. - 2 Samuel 18:19, 2 Samuel 18:20. Ahimaaz, the son of Zadok, wanted to carry the news to David, that Jehovah had "procured the king justice out of the hand of his enemies" (שׁפט with מן is a pregnant expression signifying to procure justice and deliver out of); but Joab, knowing how David would receive the tidings of the death of Absalom, replied, "Thou art no man of good tidings to-day; thou shalt take the news on another day, not on this, even because (על־כּן כּי, see at Genesis 18:5) the king's son is dead." The Keri על־כּן כּי is to be preferred to the Chethib כּי־על; and כּן has no doubt been dropt out merely because of בּן which follows. The Chethib does not give any suitable sense; for the absence of the article before מת is decisive against the explanation proposed by Maurer, viz., "for (tidings have to be carried) concerning the king's son dead." If מת were to be construed as an adverb with בּן־מלך, it would of necessity have the article.

Then said Ahimaaz the son of Zadok, Let me now run, and bear the king tidings, how that the LORD hath avenged him of his enemies.

avenged...: Heb. judged him from the hand, etc

19. Then said Ahimaaz . Let me . run and bear the king tidings-The reasons why Joab declined to accept Ahimaaz' offer to bear intelligence of the victory to David, and afterwards let him go along with another, are variously stated by commentators-but they are of no importance. Yet the alacrity of the messengers, as well as the eager excitement of the expectants, is graphically described.

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.