John Gills Exposition of the Bible Commentary - 2 Samuel 15:12
And Absalom sent for Ahithophel, the Gilonite, David's counsellor ,.... To advise with about this treasonable affair he was engaged in, and to get out of him David's secrets, who was reckoned the best counsellor in the land; and he might rather hope he would come to him, if he was the grandfather of Bathsheba, as say the Jews, 2 Samuel 11:3 ; since he might be disgusted with and resent David's adultery with Bathsheba his granddaughter, and the murder of her husband Uriah: him he sent for: ... read more
Matthew Henry's Complete Commentary - 2 Samuel 15:7-12
We have here the breaking out of Absalom's rebellion, which he had long been contriving. It is said to be after forty years, 2 Sam. 15:7. But whence it is to be dated we are not told; not from David's beginning his reign, for then it would fall in the last year of his life, which is not probable; but either from his first anointing by Samuel seven years before, or rather (I think) from the people's desiring a king, and the first change of the government into a monarchy, which might be about... read more