The foundation of this psalm is the promise in 2 Sam. vii. which guaranteed the perpetuity of the Davidic kingdom. Many of the characteristic phrases of the prophecy recur here—e.g., the promises that the children of wickedness shall not afflict, and that the transgressions of David's descendants should be followed by chastisement only, not by rejection. The contents of Nathan's oracle are first given in brief in vv. 3, 4—"like a text," as Hupfeld says—and again in detail and with poetic embellishments in vv. 19-37. But these glorious promises are set in sharpest contrast with a doleful present, which seems to contradict them. They not only embitter it, but they bewilder faith, and the psalmist's lament is made almost a reproach of God, whose faithfulness seems imperilled by the disasters which had fallen on the monarchy and on Israel. The complaint and petitions of the latter part are the true burden of the psalm, to which the celebration of Divine attributes in vv. 1-18, and the expansion of the fundamental promise in vv. 19-37, are meant to lead up. The attributes specified are those of Faithfulness (vv. 1, 2, 5, 8, 14) and of Power, which render the fulfilment of God's promises certain. By such contemplations the psalmist would fortify himself against the whispers of doubt, which were beginning to make themselves heard in his mind, and would find in the character of God both assurance that His promise shall not fail, and a powerful plea for his prayer that it may not fail.
The whole tone of the psalm suggests that it was written when the kingdom was toppling to ruin, or perhaps even after its fall. Delitzsch improbably supposes that the young king, whom loss and shame make an old man (ver. 45), is Rehoboam, and that the disasters which gave occasion to the psalm were those inflicted by the Egyptian king Shishak. Others see in that youthful prince Jehoiachin, who reigned for three months, and was then deposed by Nebuchadnezzar, and whom Jeremiah has bewailed (xxii. 24-29). But all such conjectures are precarious.
The structure of the psalm can scarcely be called strophical. There are three well-marked turns in the flow of thought,—first, the hymn to the Divine attributes (vv. 1-18); second, the expansion of the promise, which is the basis of the monarchy (vv. 19-37); and, finally, the lament and prayer, in view of present afflictions, that God would be true to His attributes and promises (vv. 38-51). For the most part the verses are grouped in pairs, which are occasionally lengthened into triplets.
The psalmist begins with announcing the theme of his song—the Loving-kindness and Faithfulness of God. Surrounded by disasters, which seem in violent contradiction to God's promise to David, he falls back on thoughts of the Mercy which gave it and the Faithfulness which will surely accomplish it. The resolve to celebrate these in such circumstances argues a faith victorious over doubts, and putting forth energetic efforts to maintain itself. This bird can sing in midwinter. True, the song has other notes than joyous ones, but they, too, extol God's Loving-kindness and Faithfulness, even while they seem to question them. Self-command, which insists on a man's averting his thoughts from a gloomy outward present to gaze on God's loving purpose and unalterable veracity, is no small part of practical religion. The psalmist will sing, because he said that these two attributes were ever in operation, and lasting as the heavens. "Loving-kindness snail be built up for ever," its various manifestations being conceived as each being a stone in the stately building which is in continual course of progress through all ages, and can never be completed, since fresh stones will continually be laid, as long as God lives and pours forth His blessings. Much less can it ever fall into ruin, as impatient sense would persuade the psalmist that it is doing in his day. The parallel declaration as to God's Faithfulness takes the heavens as the type of duration and immobility, and conceives that attribute to be eternal and fixed, as they are. These convictions could not burn in the psalmist's heart without forcing him to speak. Lover, poet, and devout man, in their several ways, feel the same necessity of utterance. Not every Christian can "sing," but all can and should speak. They will, if their faith is strong.
The Divine promise, on which the Davidic throne rests, is summed up in the abruptly introduced pair of verses (3, 4). That promise is the second theme of the psalm; and just as, in some great musical composition, the overture sounds for the first time phrases which are to be recurrent and elaborated in the sequel, so, in the four first verses of the psalm, its ruling thoughts are briefly put. Vv. 1, 2, stand first, but are second in time to vv. 3, 4. God's oracle preceded the singer's praise. The language of these two verses echoes the original passage in 2 Sam. vii., as in "David My servant, establish, for ever, build," the last three of which expressions were used in ver. 2, with a view to their recurrence in ver. 4. The music keeps before the mind the perpetual duration of David's throne.
In vv. 6-18 the psalmist sets forth the Power and Faithfulness of God, which insure the fulfilment of His promises. He is the incomparably great and terrible God, who subdues the mightiest forces of nature and tames the proudest nations (vv. 9, 10), who is Maker and Lord of the world (vv. 11, 12), who rules with power, but also with righteousness, faithfulness, and grace (vv. 13, 14), and who, therefore, makes His people blessed and safe (vv. 15-18). Since God is such a God, His promise cannot remain unfulfilled. Power and willingness to execute it to the last tittle are witnessed by heaven and earth, by history and experience. Dark as the present may be, it would, therefore, be folly to doubt for a moment.
The psalmist begins his contemplations of the glory of the Divine nature with figuring the very heavens as vocal with His praise. Not only the object but the givers of that praise are noteworthy. The heavens are personified, as in Psalm xix.; and from their silent depths comes music. There is One higher, mightier, older, more unperturbed, pure, and enduring than they, whom they extol by their lustre which they owe to Him. They praise God's "wonder" (which here means, not so much His marvellous acts, as the wonderfulness of His Being, His incomparable greatness and power), and His Faithfulness, the two guarantees of the fulfilment of His promises. Nor are the visible heavens His only praisers. The holy ones, sons of the mighty—i.e., the angels—bow before Him who is high above their holiness and might, and own Him for God alone.
With ver. 9 the hymn descends to earth, and magnifies God's Power and Faithfulness as manifested there. The sea is, as always, the emblem of rebellious tumult. Its insolence is calmed by Him. And the proudest of the nations, such as Rahab ("Pride," a current name for Egypt), had cause to own His power, when He brought the waves of the sea over her hosts, thus in one act exemplifying His sovereign sway over both nature and nations. He is Maker, and therefore Lord, of heaven and earth. In all quarters of the world His creative hand is manifest, and His praise sounds. Tabor and Hermon may stand, as the parallelism requires, for west and east, though some suppose that they are simply named as conspicuous summits. They "shout for joy at Thy Name," an expression like that used in ver. 16, in reference to Israel. The poet thinks of the softly swelling Tabor with its verdure, and of the lofty Hermon with its snows, as sharing in that gladness, and praising Him to whom they owe their beauty and majesty. Creation vibrates with the same emotions which thrill the poet. The sum of all the preceding is gathered up in ver. 13, which magnifies the might of God's arm.
But more blessed still for the psalmist, in the midst of national gloom, is the other thought of the moral character of God's rule. His throne is broad-based upon the sure foundation of righteousness and justice. The pair of attributes always closely connected—namely, Loving-kindness and Troth or Faithfulness—are here, as frequently, personified. They "go to meet Thy face"—that is, in order to present themselves before Him. "The two genii of the history of redemption (Psalm xliii. 3) stand before His countenance, like attendant maidens, waiting the slightest indication of His will" (Delitzsch).