He worketh great deliverances, etc This concluding verse clearly shows why God had exercised such goodness and liberality towards David, namely, because he had anointed him to be king. By calling himself God's king, David testifies that he had not rashly rushed into that office, nor was thrust into it by conspiracies and wicked intrigues, but, on the contrary, reigned by lawful right, inasmuch as it was the will of God that he should be king. This he proves by the ceremony of anointing; for God, in anointing him by the hand of Samuel, had asserted his right to reign not less than if he had visibly stretched forth his hand from heaven to place and establish him on the royal throne. This election, he says, was confirmed by a continued series of great deliverances; and from this it follows, that all who enter on any course without having the call of God, are chargeable with avowedly making war against him. At the same time, he attributes these deliverances to the goodness of God as their cause, to teach us, that that kingdom was founded purely and simply upon the good pleasure of God. Farther, from the concluding sentence of the psalm, it appears, as I have said before, that David does not here so much recount by way of history the singular and varied instances of the grace of God which he had personally experienced, as predict the everlasting duration of his kingdom. And it is to be observed, that by the word seed we are not to understand all his descendants indiscriminately; but we are to consider it as particularly referring to that successor of David of whom God had spoken in 2 Samuel 7:12, promising that he would be a father to him. As it had been predicted that his kingdom would continue as long as the sun and the moon should shine in the heavens, the prophecy must necessarily be viewed as descending to him who was to be king not for a time, but for ever. David, therefore, commends his seed to us, as honored by that remarkable promise, which fully applies neither to Solomon nor to any other of his successors, but to the only begotten Son of God; as the apostle, in his Epistle to the Hebrews, (Hebrews 1:4,) teaches us, that this is a dignity in which he excels the angels. In conclusion, we shall then only duly profit in the study of this psalm, when we are led by the contemplation of the shadow and type to him who is the substance.

Great deliverance giveth he to his king - To David, as king. The word in the original, which is rendered "deliverance," means properly salvations, and is here in the plural number. It refers not to one act of divine interposition, but to the many acts (referred to in the psalm) in which God had interposed to save him from danger and from death. The phrase "to his king" refers to the fact that God had appointed him to reign, and to administer the government for him. He did not reign on his own account, but he reigned for God, and with a view to do his will.
And showeth mercy to his anointed - To him who had been set apart to the kingly office by a solemn act of anointing. Compare 1-Samuel 16:13; 2-Samuel 2:4-7; 2-Samuel 5:3, 2-Samuel 5:17; 2-Samuel 12:7; compare 2-Kings 9:3, 2-Kings 9:6,2-Kings 9:12. It is in allusion to this custom that the Messiah is called the Anointed, or the Christ. See the note at Matthew 1:1.
To David, and to his seed - To his descendants, or posterity. There is an undoubted reference here to the promises made to David in regard to his successors on the throne. See 2-Samuel 7:12-16, 2-Samuel 7:25-26, and Ps. 89:19-37.
Forevermore - This expresses the confident expectation of David that the government would remain in his family to the latest times. This expectation was founded on such promises as that in 2-Samuel 7:12-13 : "I will set up thy seed after thee, which shall proceed out of thy bowels, and I will establish his kingdom; he shall build an house for my name, and I will establish the throne of his kingdom forever." Also 2-Samuel 7:16 : "And thine house and thy kingdom shall be established forever before thee; thy throne shall be established forever." See also Psalm 89:36 : "His seed shall endure forever, and his throne as the sun before me." The perpetuity of this kingdom is found, in fact, in the reign of the Messiah, a descendant of David, in whose eternal reign these promises will receive an ample fulfillment. See Isaiah 9:7. Compare Luke 1:32-33. The temporal reign passed wholly away in the process of time from the descendants of David; the spiritual reign is perpetual in the Messiah. How far David understood this it is not important to inquire, and it would be impossible to determine. It is sufficient for the proper understanding of the place to remember
(a) that there will have been a strict fulfillment of the promise, according to the full import of the language, in the Messiah, the Son of David; and
(b) that, however this may have been understood by David who recorded the promise, the real author of the promise was the Holy Spirit, and that the real meaning of the promise, as thus recorded, was that it should be fulfilled as it has been.
In this, as in all other cases, the inquiry to be made in interpreting the language is not how the sacred penman understood it, but what was meant by the real author, the Spirit of God - and whether the prediction, according to that meaning, has been fulfilled. When a man employs an amanuensis, the inquiry in regard to what is written is not how the amanuensis understood it, but how he who dictated what was written intended it should be understood. Applying this principle, the prediction here and elsewhere, in regard to the perpetuity of the reign of David and his posterity, has been, and is, fulfilled in the most ample manner. "Great David's greater Son" shall reign forever and ever.

Great deliverance giveth he to his king - David was a king of God's appointment, and was peculiarly favored by him. Literally, He is magnifying the salvations of his king. He not only delivers, but follows up those deliverances with innumerable blessings.
Showeth mercy - to David - I have no claim upon his bounty. I deserve nothing from him, but he continues to show mercy.
To his seed - His posterity. So the words זרע zera and σπερμα, in the Old and New Testament, should be universally translated. The common translation is totally improper, and now more so than formerly, when anatomy was less understood.
For evermore - עד עולם ad olam, for ever; through all duration of created worlds. And more - the eternity that is beyond time. This shows that another David is meant, with another kind of posterity, and another sort of kingdom. From the family of David came the man Christ Jesus; his posterity are the genuine Christians; his kingdom, in which they are subjects, is spiritual. This government shall last through all time, for Christianity will continue to prevail till the end of the world: and it will be extended through eternity; for that is the kingdom of glory in which Jesus reigns on the throne of his Father, and in which his followers shall reign with him for ever and ever.
It has already been remarked that this whole Psalm has been understood as relating to the passion and victories of Christ, and the success of the Gospel in the earth. In this way Bishop Horne has understood and paraphrased it; and in the same way it is considered by the ancient Psalter, so often mentioned. Many of the primitive fathers and modern interpreters have taken the same view of it. Those passages which I judged to have this meaning I have pointed out, and have only to add that, as David was a type of Christ, many things spoken of him primarily, refer to our Lord ultimately; but much judgment and caution are required in their application. To apply the whole Psalm in this way appears to me very injudicious, and often derogatory from the majesty of Christ. Let this be my excuse for not following the same track in which many of my predecessors have gone.

Great deliverance giveth he to his king; and sheweth mercy to his anointed, to David, and to his (n) seed for evermore.
(n) This did not properly belong to Solomon, but to Jesus Christ.

Great deliverance giveth he to his king,.... Not that is king over him; for he is King of kings and Lord of lords; but that is made king by him, as David was; who did not usurp the throne, but was anointed king by the appointment of God, and was placed by him upon the throne; to whom he gave great deliverance from his enemies, or "magnified salvations" to him; which were great in kind, and many in number; and as Christ is, whom God has set as his King on his holy hill of Sion, against whom the Heathen raged, and kings and princes set themselves; but he is delivered from them all, and saved from the power of death and the grave, and ever lives to reign over, protect, and defend his people; in 2-Samuel 22:51, it is, he is "the tower of salvation for his king", with which compare Proverbs 18:10;
and showeth mercy to his anointed, to David, and to his seed for evermore; which may be understood either of David literally, who was the Lord's anointed, and to whom God showed mercy in various instances; and then by his seed is meant the Messiah, who was of his seed according to the flesh; or of the Messiah, whose name signifies Anointed; and who is often called David, Ezekiel 34:23, Hosea 3:5; and so some of the Jewish doctors (u) from this verse prove that the name of the Messiah is David: and by his seed are meant his spiritual seed; all the elect of God, who are given him as his children, to whom he stands in the relation of the everlasting Father: and as mercy is kept with him for evermore, Psalm 89:28; so it is shown to them in regeneration, in the forgiveness of their sins, and in their everlasting salvation.
(u) Echa Rabbati, fol. 50. 2.

His king - To the king whom God himself chose and anointed, and to all his posterity; and especially to the Messiah, who is called David's seed, Acts 13:23; Romans 1:3.