John Gill

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 Sa2 22:51, it is, he is "the tower of salvation for his king", with which compare Pro 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, Eze 34:23, Hos 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, Psa 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. Next: Psalms Chapter 19