John Gill Bible Commentary

Thou wilt prolong the King's life,.... Or "add days to the days of the King" (a). Meaning either himself, who, though his life was in danger by fighting with the Syrians and Edomites, or rather through the conspiracy of his son; yet was assured that he should yet live many years more, and especially in his posterity; and that his kingdom would be established for ever, as was promised him, Sa2 7:12. Or rather the King Messiah, so the Targum: and Kimchi observes, that if this psalm respects the captivity, the King is the King Messiah: it may be understood of his life as man; who, though he died, rose again, and lives for evermore; and that, as to the glory of God the Father, so to the good of his people, for whom he makes intercession; and of the continuance of his spiritual seed, in whom he may be said to live, and his days be prolonged, Isa 53:10; and of the duration of his kingdom, of which there will be no end. For it is an everlasting one, as follows: and his years as many generations; he living, and his posterity and kingdom continuing, age after age. The Targum is, "his years as the generations of this world, and the generations of the world to, come.'' (a) "dies super dies regis adjicieo", V. L. Pagninus, Montanus, &c.