The kingdom in relation to its subjects is the theme of ver. 3, which accords with the warlike tone of the whole psalm, by describing them as an army. The period spoken of is "the day of Thy host," or array--the time when the forces are mustered and set in order for battle. The word rendered _free-will offerings_ may possibly mean simply "willingnesses," and the abstract noun may be used as in "I am--prayer" (Psalm cix. 4)--_i.e._, most willing; but it is better to retain the fuller and more picturesque meaning of glad, spontaneous sacrifices, which corresponds with the priestly character afterwards ascribed to the people, and goes very deep into the essence of Christian service. There are to be no pressed men or mercenaries in that host. As Deborah sang of her warriors, these "offer themselves willingly." Glad consecration of self, issuing in spontaneous enlisting for the wars of the King, is to characterise all His subjects. The army is the nation. These soldiers are to be priests. They are clad in holy attire, "fine linen, clean and white." That representation goes as deep into the nature of the warfare they have to wage and the weapons they have to wield, as the former did into the impulse which sends them to serve under Messiah's flag. The priestly function is to bring God and man near to one another. Their warfare can only be for the carrying out of their office. Their weapons are sympathy, gentleness, purity. Like the Templars, the Christian soldier must bear the cross on his shield and the hilt of his sword. Another reading of this phrase is "on the holy mountains," which is preferred by many, among whom are Hupfeld and Cheyne. But the great preponderance of evidence is against the change, which obliterates a very striking and profound thought.
Ver. 3_c_, _d_ gives another picture of the host. The usual explanation of the clause takes "youth" as meaning, not the young vigour of the King, but, in a collective sense, the assembled warriors, whom it paints as in the bloom of early manhood. The principal point of comparison of the army with the dew is probably its multitude (2 Sam. xvii. 12). The warriors have the gift of un-aging youth, as all those have who renew their strength by serving Christ. And it is permissible to take other characteristics of the dew than its abundance, and to think of the mystery of its origin, of the tiny mirrors of the sunshine hanging on every cobweb, of its power to refresh, as well as of the myriads of its drops.
But this explanation, beautiful and deep as it is, is challenged by many. The word rendered "dawn" is unusual. "Youth" is not found elsewhere in the sense thus assigned to it. "Dew" is thought to be an infelicitous emblem. "From a linguistic point of view" Cheyne pronounces both "dawn" and "dew" to be intolerable. Singularly enough, in the next sentence, he deprecates a previous opinion of his own as premature "until we know something certain of the Hebrew of the Davidic age" ("Orig. of Psalt.," p. 482). But if such certainty is lacking, why should these two words be "intolerable"? He approves Bickell's conjectural emendation, "From the womb, from the dawn [of life], Thy youthful band is devoted to Thee."
Ver. 4 again enshrines a Divine utterance, which is presented in an even more solemn manner than that of ver. 1. The oath of Jehovah by Himself represents the thing sworn as guaranteed by the Divine character. God, as it were, pledges His own name, with its fulness of unchanging power, to the fulfilment of the word; and this irrevocable and omnipotent decree is made still more impressive by the added assurance that He "will not repent." Thus inextricably intertwined with the augustness of God's nature, the union of the royal and priestly offices in the person of Messiah shall endure for ever. Some commentators contend that every theocratic king of Israel was a priest, inasmuch as he was king of a priestly nation. But since the national priestliness did not hinder the appointment of a special order of priests, it is most natural to assume that the special order is here referred to. Why should the singer have gone back into the mists of antiquity, in order to find the type of a priest-king, if the union of offices belonged, by virtue of his kinghood, to every Jewish monarch? Clearly the combination was unexampled; and such an incident as that of Uzziah's leprosy shows how carefully the two great offices were kept apart. Their opposition has resulted in many tragedies: probably their union would be still more fatal, except in the case of One whose priestly sacrifice of Himself as a willing offering is the basis of His royal sway. The "order of Melchizedek" has received unexpected elucidation from the Tel-el-Amarna tablets, which bring to light, as a correspondent of the Pharaoh, one Ebed-tob, king of Uru-salim (the city of Salim, the god of peace). In one of his letters he says, "Behold, neither my father nor my mother have exalted me in this place; the prophecy [or perhaps, arm] of the mighty King has caused me to enter the house of my father." By the mighty King is meant the god whose sanctuary stood on the summit of Mount Moriah. He was king of Jerusalem, because he was priest of its god (Sayce, "Criticism and the Monuments," p. 175). The psalm lays stress on the eternal duration of the royalty and priesthood of Messiah; and although in other Messianic psalms the promised perpetuity may be taken to refer to the dynasty rather than the individual monarch, that explanation is impossible here, where a person is the theme.