Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
And it came to pass ... - The working out of Nathan's prophecy (marginal reference) is the clue to the course of the narrative. How long after Absalom's return these events occurred we are not told.
Beside the way of the gate - See Rut 4:1 note.
To flatter each man by pronouncing a favorable verdict in his case, to excite a sense of grievance and discontent by censuring the king for remissness in trying the causes brought before him by his subjects, and to suggest a sure and easy remedy for all such grievances, namely, to make Absalom king; all this, coupled with great affability and courtesy, which his personal beauty and high rank made all the more effective, were the arts by which Absalom worked his way into favor with the people, who were light and fickle as himself.
Stole the hearts - i. e., deceived them, for so the same phrase means Gen 31:20, Gen 31:26.
Forty years - An obvious clerical error, though a very ancient one for four years, which may date from Absalom's return from Geshur, or from his reconciliation with David, or from the commencement of the criminal schemes to which Sa2 15:1 refers.
Hebron - This, as having been the old capital of David's kingdom and Absalom's birthplace, was well chosen. It was a natural center, had probably many inhabitants discontented at the transfer of the government to Jerusalem, and contained many of the friends of Absalom's youth. As the place of his birth (compare Sa1 20:6), it afforded a plausible pretext for holding there the great sacrificial feast ("the serving the Lord," Sa2 15:8), which Absalom pretended to have vowed to hold to the glory of God.
Ahithophel - It has been with great probability supposed that Ahithophel was estranged from David by personal resentment for his conduct in the matter of Bath-sheba and Uriah (see Sa2 11:3).
While he offered sacrifices - Rather, that Absalom sent for Ahithophel to be present when he offered the sacrifices; the intention being that all who partook of the sacrifice should be bound together to prosecute the enterprise. Absalom, too, would take advantage of the excitement of the great feast to inflame the ardour of the guests, and pledge them irrevocably to his cause.
And smite the city - David's kind nature induced him to spare Jerusalem the horrors of a siege, and the risk of being taken by assault. He had no standing army with which to resist this sudden attack from so unexpected a quarter. Possibly too he remembered Nathan's prophecy Sa2 12:10-12.
Passed on - Rather, "crossed" the Brook Kidron, as in Sa2 15:22-23.
Gittites - During David's residence in the country of the Philistines he attached such a band to himself; and after the settlement of his kingdom, and the subjugation of the Philistines, the band received recruits from Gath, perhaps with the king of Gath's consent. They were now under the command of Ittai the Gittite, a foreigner Sa2 15:19, and "his brethren" Sa2 15:20. The number 600 probably indicates that this band or regiment of Gittites had its origin in David's band of 600 Sa1 23:13; Sa1 27:2. They were at first, it is likely, all Israelites, then Gittites mixed with Israelites, and at last all Gittites.
Thou camest but yesterday - Meaning, "Thou art not a native Israelite, but only a sojourner for a few years, it is not reason therefore that thou shouldst share my calamities. Return to thy place, thy adopted home Jerusalem, and to the king, Absalom" Sa2 15:34-35.
Abiathar went up - i. e., continued to ascend the Mount of Olives. Abiathar was high priest Kg1 2:35. Perhaps Zadok is addressed by David Sa2 15:25 as the chief of those who were actually bearing the ark.
Art not those a seer? - If the text be correct, the sense would be, "Art thou not a seer? therefore go back to the city, and observe, and certify me of what thou seest" Sa2 15:28. Others, by a slight alteration of the original text, read "Art not thou a chief" (priest), etc.
His head covered - See the marginal references and Jer 14:3-4; Eze 24:17; the sign of deep mourning.
Render ... "when David was come to the top of the mount where people worship God." The top here, and in Sa2 16:1, is used almost as a proper name. No doubt there was a high-place upon the top of the Mount of Olives.