Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
It is David who places Solomon on the throne, who commands the princes to aid him, and who appoints prophecy in inspired psalms [See Note #1]. He ordains the age at which the Levites' service should commence-a different age from that ordained by Moses [See Note #2]. It is the whole order of the house of God and of the king, which is appointed under his hand; a new system which is established, founded upon grace as its principle.
Solomon only puts in execution the order and plans of divine wisdom in David. Glory is but the fruit of grace. It is the Christ who has suffered, who is the wisdom and the power of God, unto whom all the order of the house belongs. All the rest is glorious, but it is only a result. Only we have already seen that it is in peace, and by Christ, as Prince of peace, that this house must be built. It did not become the habitual manifestation of the glory of God, that there should be enemies to combat; neither was it suitable to the character of His people's joy. The character of such a state of things should be that of blessing -flowing without obstacle from God.
It is very important to observe how everything here is ruled by David. It is important, in the first place, morally. The intelligence, the right of ordering all things, the energy which grasps the whole thought of God, the fellowship with Him in His counsels, the germ and moral foundation of all these counsels, as well as the power of maintaining them, are connected with the sufferings which Christ underwent for the glory of His Father. This is true of us also in our measure. It is the humbled suffering Christ, who is morally on a level with all this glory. It is important, in the second place, as to intelligence in the ways of God; for I doubt not that Christ, at the commencement of His reign, will act in the character of David. We may also remark here, that the extent of authority which David exercised was very great and of wide bearing. The whole religious order was reconstructed. Everything, even to the age of the Levites' service, depends on the authority and regulations of David, as formerly on those of Moses. All the pattern of the temple, and of its vessels, is given him by inspiration, as that of the tabernacle, and all belonging to it had been given to Moses. He also introduced singing, and divers musical instruments, which are even called "the musical instruments of God," and which, as well as the singing, had previously formed no part of the public service. With the exception of the ark, even the various vessels were different from those of the tabernacle; and for each thing the precise weight in gold or in silver was determined by David.
Heman himself, apparently, was inspired also. Several psalms are ascribed to him, as well as to Asaph.
At any rate the probably probationary period of four years is not mentioned. David ordains the age by his own authority.