2-samuel 15:7

After forty years - There is no doubt that this reading is corrupt, though supported by the commonly printed Vulgate, the Septuagint, and the Chaldee. But the Syriac has arba shanin, Four years; the Arabic the same arba shinin, Four years; and Josephus has the same; so also the Sixtine edition of the Vulgate, and several MSS. of the same version. Theodoret also reads four, not forty; and most learned men are of opinion that ארבעים arbaim, Forty, is an error for אברע arba, Four; yet this reading is not supported by any Hebrew MS. yet discovered. But two of those collated by Dr. Kennicott have יום yom instead of שנה shanah, i.e., forty Days, instead of forty Years; and this is a reading more likely to be true than that in the commonly received text. We know that Absalom did stay Three years with his grandfather at Geshur, 2 Samuel 13:38; and this probably was a year after his return: the era, therefore, may be the time of his slaying his brother Amnon; and the four years include the time from his flight till the conspiracy mentioned here.

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 2 Samuel 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 1 Samuel 20:6), it afforded a plausible pretext for holding there the great sacrificial feast ("the serving the Lord," 2 Samuel 15:8), which Absalom pretended to have vowed to hold to the glory of God.

15:7 After forty years - From the change of the government, into a monarchy, which was about ten years before David began to reign.So this fell out about the thirtieth year of his reign.