Albert Barnes Commentary Psalms 89

I will sing of the mercies of the Lord for ever - Particularly how the mercy was manifested in the promise made to David; the solemn covenant made with him regarding the perpetuity of his throne. The appointment of David to the throne was an act of mere mercy or favor, since he was not in the royal line and had no claim to the crown. It will also be seen that if it is supposed that the covenant with David, and the promise made in it to him, was intended to include the Messiah as descending from him, there was a still higher reason for celebrating the mercies of God, since all mercy to our world comes through him.

With my mouth - Not merely in my heart, but with words. The meaning here is that he would make a record which might be used forever as the language of praise.

Will I make known your faithfulness - In the fulfillment of these promises. He felt assured that they would be fulfilled. Whatever appearances there might be to the contrary, the psalmist had no doubt that God would prove himself to be faithful and true. See the notes at Isaiah 55:3, on the expression, the sure mercies of David.

To all generations - Margin, as in Hebrew, generation and generation. He would make a record which would carry down the remembrance of this faithfulness to all future ages.

For I have said — The Septuagint and the Latin Vulgate render this, “You have said,” which is more in accordance with what the connection seems to demand, but the Hebrew will not admit of this construction. The true meaning seems to be that the psalmist had said—that is, he had said in his mind; he had firmly believed; he had so received it as a truth that it might be spoken of as firmly settled or as an indisputable reality. It was in his mind one of the things whose truthfulness did not admit of a doubt.

Mercy shall be built up for ever — The mercy referred to—the mercy manifested in the promise made to David. The idea is that the promise would be fully carried out or verified. It would not be like the foundation of a building which, after being laid, was abandoned; it would be as if the building for which the foundation was designed were carried up and completed. It would not be a forsaken, half-finished edifice, but an edifice fully erected.

Your faithfulness you shall establish — In the matter referred to—the promise made to David.

In the very heavens — Literally, “The heavens—you will establish your faithfulness in them.” That is, the heavens—the heavenly bodies—so regular, so fixed, so enduring, are looked upon as the emblem of stability. The psalmist brings them thus before his mind, and he says that God had, as it were, made His promise a part of the very heavens; He had given His faithfulness a place among the most secure, and fixed, and settled objects in nature. The sun in its regular rising; the stars in their certain course; the constellations, the same from age to age, were an emblem of the stability and security of the promises of God. .

I have made a covenant with my chosen — With my chosen one; that is, with David. The original is in the singular number, though by the Septuagint, the Vulgate, and Luther, it is rendered in the plural—'chosen ones,' 'elect.' This is undoubtedly the language of God himself, though it is not expressly ascribed to him. The design is to describe the solemn promise which God had made to David and to his posterity. Compare Psalms 78:70-71. See also, on the use of the phrase “made a covenant,” see Psalms 50:5, note; Psalms 83:5, note.

I have sworn unto David my servant — I have taken a solemn oath in regard to him. The substance of the oath is stated in the next verse. The promise referred to is found in 2 Samuel 7:11–16.

Thy seed will I establish for ever - Your children; your 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).

And the heavens shall praise thy wonders, O Lord — That is, the inhabitants of heaven will find new occasion for praise in the faithfulness demonstrated in carrying out the promise to David, and in the marvelous things that will occur under that promise, and in its accomplishment. If we suppose that this promise embraced the Messiah and his reign, then we will see what new occasions the angels would find for praise: in the incarnation of the Redeemer, and in all that would be accomplished by him.

Thy faithfulness also in the congregation of the saints — In the assembly of the holy ones; that is, the angels. In their songs of praise, this will be among the things that will fill them with joy. The idea is that the inhabitants of the heavens—the holy angels—would take a deep interest in the fulfillment of this promise, as it would provide new manifestations of the character of God. (1 Peter 1:12.)