I have made a covenant with my elect: I have sworn to David my servant:

“Let us see then what God has sworn. "I have sworn," He says, "to David My servant; your seed will I establish for ever" [Psalm 89:4]. But what is the seed of David, but that of Abraham. And what is the seed of Abraham? "And to your seed," He says, "which is Christ." [Galatians 3:16] But perhaps that Christ, the Head of the Church, the Saviour of the body, [Ephesians 5:23] is the seed of Abraham, and therefore of David; but we are not Abraham's seed? We are assuredly; as the Apostle says, "And if you be Christ's, then are you Abraham's seed, and heirs according to the promise." [Galatians 3:29] In this sense, then, let us take the words, brethren, "Your seed will I establish for ever," not only of that Flesh of Christ, born of the Virgin Mary, but also of all of us who believe in Christ, for we are limbs of that Head. This body cannot be deprived of its Head: if the Head is in glory for ever, so are the limbs, so that Christ remains entire for ever. "Your seed will I establish for ever: and set up your throne to generation and generation." We suppose he says, "for ever," because it is "to generation and generation:" since he has said above, with "my mouth will I ever be showing Your truth to generation and generation." What is "to generation and generation"? To every generation: for the word needed not as many repetitions, as the coming and passing away of the several generations. The multiplication of generations is signified and set forth to notice by the repetition. Are possibly two generations to be understood, as you are aware, my beloved brethren, and as I have before explained? For there is now a generation of flesh and blood: there will be a future generation in the resurrection of the dead. Christ is proclaimed here: He will be proclaimed there: here He is proclaimed, that He may be believed in: there, He will be welcomed, that He may be seen. "I will set up Your throne from one generation to another." Christ has now a throne in us, His throne is set up in us: for unless he sat enthroned within us, He would not rule us: but if we were not ruled by Him, we should be thrown down by ourselves. He therefore sits within us, reigning over us: He sits also in another generation, which will come from the resurrection of the dead. Christ will reign for ever over His Saints. God has promised this; He has said it: if this is not enough, God has sworn it. As then the promise is certain, not on account of our deservings, but of His pity, no one ought to be afraid in proclaiming that which he cannot doubt of. Let that strength then inspire our hearts, whence Æthan received his name, "strong in heart:" let us preach the truth of God, the utterance of God, His promises, His oath; and let us, strengthened on every side by these means, glorify God, and by bearing Him along with us, become Heavens.”

“And the heavens shall praise thy wonders, O Lord,.... Which, by a prosopopceia, may be understood of the heavens literally, in the same sense as other inanimate creatures praise the Lord, Psa 148:3, or mystically of the church, consisting of heaven born souls, and whose doctrines and ordinances are from heaven; or of the apostles, as Jerom, who had their ministry, mission, commission, and gifts, from thence; or rather of the angels, the inhabitants of heaven, who praise the Lord for his wonderful works of nature, providence, and grace, Psa 148:2, particularly they admire and praise the wonderful work of redemption "that wonderful thing of thine" (m), as the word may be rendered, being in the singular number: the person of the Redeemer is wonderful, and that is his name; his incarnation is a most amazing thing, it is the great mystery of godliness; and the redemption wrought out by him is the wonder of men and angels: when he appeared in the world, the angels of God worshipped him; at his birth, they sung glory to God in the highest; and the mysteries of his grace are what they look into with wonder and praise, Heb 1:6, thy faithfulness also in the congregation of the saints; i.e. is praised there; which Aben Ezra and Kimchi interpret of the angels also, who are called saints, Deu 33:2, of which there is a congregation, even an innumerable company, Rev 19:6, these not only admire and praise the wonderful works of the Lord, but his perfections also; and particularly his faithfulness in the execution of promises and threatenings, Rev 7:11, but rather holy men are meant, such as are called to be saints, and are gathered together in a Gospel church state, designed by a congregation of them, among and by whom the truth and faithfulness of God, as well as his lovingkindness and mercy, are spoken of with the highest commendation, Psa 40:9. (m) "mirabile tuum", Pagninus, Montanus, Cocceius, Gerjus; "mirabile apus tuum", Junius & Tremellius; "illud miraculum tuum", Michaelis.”