Thy seed will I establish for ever, and build up thy throne to all generations - And this covenant had most incontestably Jesus Christ in view. This is the seed, or posterity, that should sit on the throne, and reign for ever and ever. David and his family are long since become extinct; none of his race has sat on the Jewish throne for more than two thousand years: but the Christ has reigned invariably since that time, and will reign till all his enemies are put under his feet; and to this the psalmist says Selah. It will be so, it is so; and it cannot be otherwise; for the Lord hath sworn that he shall have an euerlasting kingdom, as he has an everlasting priesthood.
Thy seed will I establish for ever - Thy children; thy posterity. The reference is to his successors on the throne. The promise was that there should not fail to be one on his throne; that is, that his dynasty should never become extinct. See 2 Samuel 7:16: “And thy house and thy kingdom shall be established forever before thee: thy throne shall be established forever.” Compare also 1 Kings 2:4. The word rendered “establish” means properly to fit; then, to make firm; to put on a solid basis.
And build up thy throne - It shall be kept up; it shall be like a building that is constantly progressing toward completion. The meaning is, that it would not fail. He would not begin the work, and then abandon it. The dynasty, the kingdom, the throne, would be complete and perpetual.
To all generations - As long as the world should stand. This can have been accomplished only by the Messiah occupying in a spiritual sense the throne of “his father David.” Compare Luke 1:32-33.