John Gill

For thy word's sake,.... For the sake of the promise he had made to him by Samuel, that he should be king, and his kingdom should be established; or for the sake of the Messiah, that should spring from him; the Memra, as the Targum, the essential Word of God; and so the Septuagint version, "because of thy servant", with which agrees the parallel text in Ch1 17:19, and according to thine own heart; of his own sovereign good will and pleasure, of his own grace, as the Arabic version, and not according to the merits and deserts of David: hast thou done all these great things; in making him king of Israel, and settling the kingdom in his posterity to the times of the Messiah, who should spring from him: to make thy servant know them; as he now did by Nathan the prophet, what he and his should enjoy for time to come; so that it is not only a blessing to have favours designed, purposed, and promised, but to have the knowledge of them, to know the things that are freely given of God.