They saw it - That is, they looked on it; they contemplated it; they were struck with its beauty and strength, and fled.
And so they marveled - It surpassed their expectations of its strength, and they saw with wonder that any attempt to conquer it was hopeless.
They were troubled - They were filled with anxiety and confusion. They even began to have apprehensions about their own safety. They saw that their preparations had been made in vain, and that all hopes of success must be abandoned.
And hasted away - They fled in confusion. The idea in the whole verse is that of a "panic," leading to a disorderly flight. This "may" have occurred in the time of Jehoshaphat, 2 Chr. 20, when the kings of Moab, Edom, and others, came up to attack Jerusalem, though the immediate cause of their overthrow was a conflict among themselves 2-Chronicles 20:22-25. It may have been, however, that they approached the city, and were dismayed by its strength, so that they turned away before the internal conflict occurred which ended in their ruin. But it is not "necessary" to adjust these accounts one to another, or even to suppose that this was the event referred to in the psalm, though the general ideas in it accord well with all which occurred on that occasion.

They saw [(f) it, and] so they marvelled; they were troubled, [and] hasted away.
(f) The enemies were afraid at the sight of the city.

They saw it,.... Either the city or the power of God, as Aben Ezra; or, as Jarchi, God himself going forth to fight against the nations. This refers to the power Christ will take to himself, and show forth, by reigning in his church, and protecting it, which will not only be visible to the saints, but to the nations of the world; and to the brightness of Christ's coming in his spiritual reign, with the lustre of which antichrist will be destroyed, Revelation 11:17; and to the glorious state of the church, signified by the rising of the witnesses, and their standing on their feet, and ascending to heaven, which will be seen by their enemies, Revelation 11:11; and to the destruction of Rome, the smoke of whose burning, the kings of the earth, that have committed fornication with her, will see and lament, Revelation 18:8;
and so their marvelled: at the glory of the church, the security of it, the power of Christ in it and over it, and at the destruction of mystical Babylon; see Isaiah 52:14;
they were troubled: as Herod and all Jerusalem were, upon hearing of the birth of Christ, Matthew 2:3; so these kings will be, upon seeing the coming and power of Christ in the latter day, the invincibleness of his church, and their own immediate and utter ruin: this will be the time or the howling of the shepherds, both civil and ecclesiastical, when all hands will be faint, and every man's heart will melt, Zac 11:2;
and hasted away: fled for fear of the great King at the head of his armies, in the defence of his church and people: and as the kings of the earth also at the destruction of Rome will flee and stand afar off, for fear of her torment, Revelation 18:10.

Saw it - They did only look upon it, but not come into it, nor shoot an arrow there - nor cast a bank against it, 2-Kings 19:32. Marvelled - At the wonderful works wrought by God.