John Gill's Bible Commentary Ver. 8. For thy servant vowed a vow while I abode at Geshur in Syria , etc.] When at his grandfather’s court there: saying, if the Lord will bring me again indeed to Jerusalem ; which he might be sincerely desirous of: then I will serve the Lord ; but it is a question whether he ever made a vow to this purpose, or concerned himself about serving the Lord; but it rather may be, this was a lie of his, now framed in order to get leave of the king to go to Hebron.
Matthew Henry Commentary
Verses 7-12 - See how willing tender parents are to believe the best concerning their children. But how easy and how wicked is it, for children to tak advantage of good parents, and to deceive them with the show of religion! The principal men of Jerusalem joined Absalom's feast upo his sacrifice. Pious persons are glad to see others appear religious and this gives occasion for deceptions. The policy of wicked men, an the subtlety of Satan, are exerted to draw good persons to countenanc base designs.
Original Hebrew כי3588 נדר5088 נדר5087 עבדך5650 בשׁבתי3427 בגשׁור1650 בארם758 לאמר559 אם518 ישׁיב7725 ישׁיבני7725 יהוה3068 ירושׁלם3389 ועבדתי5647 את853 יהוה׃3068