I. The covenant of royalty shall be secured and the promises of it shall have their full accomplishment in the kingdom of Christ, the Son of David, v. 17. The throne of Israel was overturned in the captivity; the crown had fallen from their head; there was not a man to sit on the throne of Israel; Jeconiah was written childless. After their return the house of David made a figure again; but it in the Messiah that this promise is performed that David shall never want a man to sit on the throne of Israel, and that David shall have always a son to reign upon his throne. For as long as the man Christ Jesus sits on the right hand of the throne of God, rules the world, and rules it for the good of the church, to which he is a quickening head, and glorified head over all things, as long as he is King upon the holy hill of Zion, David does not want a successor, nor is the covenant with him broken. When the first-begotten was brought into the world it was declared concerning him, The Lord God shall give him the throne of his father David and he shall reign over the house of Jacob for ever, Luke i. 32, 33. For the confirmation of this it is promised, 1. That the covenant with David shall be as firm as the ordinances of heaven, to the stability of which that of God's promise is compared, ch. xxxi. 35, 36. There is a covenant of nature, by which the common course of providence is settled and on which it is founded, here called a covenant of the day and the night (v. 20, 25), because this is one of the articles of it, That there shall be day and night in their season, according to the distinction put between them in the creation, when God divided between the light and the darkness, and established their mutual succession, and a government to each, that the sun should rule by day and the moon and stars by night (Gen. i. 4, 5, 16), which establishment was renewed after the flood (Gen. viii. 22), and has continued ever since, Ps. xix. 2. The morning and the evening have both of them their regular outgoings (Ps. lxv. 8); the day-spring knows its place, knows its time, and keeps both, so do the shadows of the evening; and, while the world stands, this course shall not be altered, this covenant shall not be broken. The ordinances of heaven and earth (of this communication between heaven and earth, the dominion of these ordinances of heaven upon the earth), which God has appointed (v. 25; compare Job xxxviii. 33), shall never be disappointed. Thus firm shall the covenant of redemption be with the Redeemer—God's servant, but David our King, v. 21. This intimates that Christ shall have a church on earth to the world's end; he shall see a seed in which he shall prolong his days till time and day shall be no more. Christ's kingdom is an everlasting kingdom; and when the end cometh, and not till then, it shall be delivered up to God, even the Father. But it intimates that the condition of it in this world shall be intermixed and counterchanged, prosperity and adversity succeeding each other, as light and darkness, day and night. But this is plainly taught us, that, as sure as we may be that, though the sun will set tonight, it will rise again tomorrow morning, whether we live to see it or no, so sure we may be that, though the kingdom of the Redeemer in the world may for a time be clouded and eclipsed by corruptions and persecutions, yet it will shine forth again, and recover its lustre, in the time appointed. 2. That the seed of David shall be as numerous as the host of heaven, that is, the spiritual seed of the Messiah, that shall be born to him by the efficacy of his gospel and his Spirit working with it. From the womb of the morning he shall have the dew of their youth, to be his willing people, Ps. cx. 3. Christ's seed are not, as David's were, his successors, but his subjects; yet the day is coming when they also shall reign with him (v. 22): As the host of heaven cannot be numbered, so will I multiply the seed of David, so that there shall be no danger of the kingdom's being extinct, or extirpated, for want of heirs. The children are numerous; and, if children, then heirs.