Adam Clarke on 2 Samuel 13:39

David longed to go forth unto Absalom - We find that he had a very strong paternal affection for this young man, who appears to have had little to commend him but the beauty of his person. David wished either to go to him, or to bring him back; for the hand of time had now wiped off his tears for the death of his son Amnon. Joab had marked this disposition, and took care to work on it, in order to procure the return of Absalom. It would have been well for all parties had Absalom ended his days at Geshur. His return brought increasing wretchedness to his unfortunate father. And it may be generally observed that those undue, unreasonable paternal attachments are thus rewarded.