The psalmist has a very sad complaint to make of the deplorable condition of the family of David at this time, and yet he begins the psalm with songs of praise; for we must, in every thing, in every state, give thanks; thus we must glorify the Lord in the fire. We think, when we are in trouble, that we get ease by complaining; but we do more - we get joy, by praising. Let our complaints therefore be turned into thanksgivings; and in these verses we find that which will be matter of praise and thanksgiving for us in the worst of times, whether upon a personal or a public account, 1. However it be, the everlasting God is good and true, Psa 89:1. Though we may find it hard to reconcile present dark providences with the goodness and truth of God, yet we must abide by this principle, That God's mercies are inexhaustible and his truth is inviolable; and these must be the matter of our joy and praise: "I will sing of the mercies of the Lord for ever, sing a praising song to God's honour, a pleasant song for my own solace, and Maschil, an instructive song, for the edification of others." We may be for ever singing God's mercies, and yet the subject will not be drawn dry. We must sing of God's mercies as long as we live, train up others to sing of them when we are gone, and hope to be singing them in heaven world without end; and this is singing of the mercies of the Lord for ever. With my mouth, and with my pen (for by that also do we speak), will I make known thy faithfulness to all generations, assuring posterity, from my own observation and experience, that God is true to every word that he has spoken, that they may learn to put their trust in God, Psa 78:6. 2. However it be, the everlasting covenant is firm and sure, Psa 89:2-4. Here we have, (1.) The psalmist's faith and hope: "Things now look black, and threaten the utter extirpation of the house of David; but I have said, and I have warrant from the word of God to say it, that mercy shall be built up for ever." As the goodness of God's nature is to be the matter of our song (Psa 89:1), so much more the mercy that is built for us in the covenant; it is still increasing, like a house in the building up, and shall still continue our rest for ever, like a house built up. It shall be built up for ever; for the everlasting habitations we hope for in the new Jerusalem are of this building. If mercy shall be built for ever, then the tabernacle of David, which has fallen down, shall be raised out of its ruins, and built up as in the days of old, Amo 9:11. Therefore mercy shall be built up for ever, because thy faithfulness shalt thou establish in the very heavens. Though our expectations are in some particular instances disappointed, yet God's promises are not disannulled; they are established in the very heavens (that is, in his eternal counsels); they are above the changes of this lower region and out of the reach of the opposition of hell and earth. The stability of the material heavens is an emblem of the truth of God's word; the heavens may be clouded by vapours arising out of the earth, but they cannot be touched, they cannot be changed. (2.) An abstract of the covenant upon which this faith and hope are built: I have said it, says the psalmist, for God hath sworn it, that the heirs of promise might be entirely satisfied of the immutability of his counsel. He brings in God speaking (Psa 89:3), owning, to the comfort of his people, "I have made a covenant, and therefore will make it good." The covenant is made with David; the covenant of royalty is made with him, as the father of his family, and with his seed through him and for his sake, representing the covenant of grace made with Christ as head of the church and with all believers as his spiritual seed. David is here called God's chosen and his servant; and, as God is not changeable to recede from his own choice, so he is not unrighteous to cast off one that served him. Two things encourage the psalmist to build his faith on this covenant: - [1.] The ratification of it; it was confirmed with an oath: The Lord has sworn, and he will not repent. [2.] The perpetuity of it; the blessings of the covenant were not only secured to David himself, but were entailed on his family; it was promised that his family should continue - Thy seed will I establish for ever, so that David shall not want a son to reign (Jer 33:20, Jer 33:21); and that it should continue a royal family - I will build up thy throne to all generations, to all the generations of time. This has its accomplishment only in Christ, of the seed of David, who lives for ever, to whom God has given the throne of his father David, and of the increase of whose government and peace there shall be no end. Of this covenant the psalmist will return to speak more largely, Psa 89:19, etc.

I will sing of the mercies of the Lord for ever,.... Both temporal and spiritual, especially the latter, in which there is a large display of the rich and abundant mercy of God, from whence they are so called; as in the choice of men to everlasting life, who are said to be vessels of mercy; in the covenant of grace made with them, the blessings of which are the sure mercies of David; in the mission of Christ, whose coming, as the dayspring from on high, is owing to the tender mercy of our God; in redemption by him, in which mercy and truth have met together; in regeneration, which is according to abundant mercy; in the forgiveness of sins, which is according to the multitude of his tender mercies; and in the whole of salvation, which is not by works of righteousness, but by the mercy of God through Christ: the word may be rendered "graces, kindnesses, goodnesses" (l), and designs the abundance of grace; as in the heart of God, in the covenant, in the hands of Christ, as displayed through him, and in the several parts of salvation, and the whole of it: and these are a proper subject for a song; and a truly gracious soul, sensible of these things, thankful for them, cheerful on account of them, and seeing his interest in them, cannot but "sing" of them; and will determine to do it "for ever", every day, and all the day long, as long as he lives, and while he has any being, and which he will do to all eternity:

with my mouth will I make known thy faithfulness to all generations; God is faithful to himself, to all the perfections of his nature, to his truth, holiness, and justice, he cannot deny himself; he is so to his Son, and to all engagements with him, and promises to him; to all his counsels, purposes, and decrees; all which are faithfulness and truth, or faithfully and truly performed; and to his covenant and promises made to his people in Christ, in whom they are all yea and amen: and that this glorious perfection of God might be made known to the saints in all successive generations, and be taken notice of by them, the psalmist spoke and sung this psalm with his mouth, and penned it with his hand; in which there is more mention made of the faithfulness of God than perhaps in any other passage of Scripture besides; see Psa 89:2.

(k) Works, vol. i. p. 699, 700. (l) "bonitates", Tigurine version; "benignitates", Junius & Tremellius; "beneficia", Piscator; "gratias", Cocceius.