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 1 Chronicles 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.

"For Thy word's sake, and according to Thy heart (and therefore not because I am worthy of such grace), has Thou done all this greatness, to make it known to Thy servant." The word, for the sake of which God had done such great things for David, must be some former promise on the part of God. Hengstenberg supposes it to refer to the word of the Lord to Samuel, "Rise up and anoint him" (1 Samuel 16:12), which is apparently favoured indeed by the parallel in the corresponding text of 1 Chronicles 17:19, "for Thy servant's sake," i.e., because Thou hast chosen Thy servant. But even this variation must contain some special allusion which does not exclude a general interpretation of the expression "for Thy word's sake," viz., an allusion to the earlier promises of God, or the Messianic prophecies generally, particularly the one concerning Judah in Jacob's blessing (Genesis 49:10), and the one relating to the ruler out of Jacob in Balaam's sayings (Numbers 24:17.), which contain the germs of the promise of the everlasting continuance of David's government. For the fact that David recognised the connection between the promise of God communicated to him by Nathan and Jacob's prophecy in Genesis 49:10, is evident from 1 Chronicles 28:4, where he refers to his election as king as being the consequence of the election of Judah as ruler. "According to Thine own heart" is equivalent to "according to Thy love and grace; for God is gracious, merciful, and of great kindness and truth" (Exodus 34:6, compare Psalm 103:8). גּדוּלה does not mean great things, but greatness.

The praise of God commences in 2 Samuel 7:22 : "wherefore Thou art great, Jehovah God; and there is not (one) like Thee, and no God beside Thee, according to all that we have heard with our ears." By the word "wherefore," i.e., because Thou hast done this, the praise of the singleness of God is set forth as the result of David's own experience. God is great when He manifests the greatness of His grace to men, and brings them to acknowledge it. And in these great deeds He proves the incomparable nature of His Deity, or that He alone is the true God. (For the fact itself, compare Exodus 15:11; Deuteronomy 3:24; Deuteronomy 4:35.)

For thy word's sake, and according to thine own heart, hast thou done all these great things, to make thy servant know them.

7:21 Thy word's sake - That thou mightest fulfil thy promises made to me, and thereby demonstrate thy faithfulness. Own heart - Or thy own mere liberality and good pleasure, without any desert of mine. So far was David, though a very gracious man, from thinking his actions meritorious.

7:18-29 David's prayer is full of the breathings of devout affection toward God. He had low thoughts of his own merits. All we have, must be looked upon as Divine gifts. He speaks very highly and honourably of the Lord's favours to him. Considering what the character and condition of man is, we may be amazed that God should deal with him as he does. The promise of Christ includes all; if the Lord God be ours, what more can we ask, or think of? Eph 3:20. He knows us better than we know ourselves; therefore let us be satisfied with what he has done for us. What can we say more for ourselves in our prayers, than God has said for us in his promises? David ascribes all to the free grace of God. Both the great things He had done for him, and the great things He had made known to him. All was for his word's sake, that is, for the sake of Christ the eternal Word. Many, when they go to pray, have their hearts to seek, but David's heart was found, that is, it was fixed; gathered in from its wanderings, entirely engaged to the duty, and employed in it. That prayer which is from the tongue only, will not please God; it must be found in the heart; that must be lifted up and poured out before God. He builds his faith, and hopes to speed, upon the sureness of God's promise. David prays for the performance of the promise. With God, saying and doing are not two things, as they often are with men; God will do as he hath said. The promises of God are not made to us by name, as to David, but they belong to all who believe in Jesus Christ, and plead them in his name.