For thy servant's sake; in 2 Samuel 7:21, it is, for thy word's sake, i.e. for the sake of thy word and promise made to thy servant; as that phrase, for David's sake, is oft thus understood, for God's covenant's sake made with David.
Related Commentaries of 1 Chronicles 17:19
1 Chronicles 17:19
19 O LORD, for thy servant's sake, and according to thine own heart, hast thou done all this greatness, in making known all these great things.