Psalms 18:7

Then the earth shook and trembled - The description which follows here is one of the most sublime that is to be found in any language. It is taken from the fury of the storm and tempest, when all the elements are in commotion; when God seems to go forth in the greatness of his majesty and the terror of his power, to prostrate everything before him. We are not to regard this as descriptive of anything which literally occurred, but rather as expressive of the fact of the divine interposition, as if he thus came forth in the greatness of his power. There is no improbability indeed in supposing that in some of the dangerous periods of David’s life, when surrounded by enemies, or even when in the midst of a battle, a furious tempest may have occurred that seemed to be a special divine interposition in his behalf, but we have no distinct record of such an event, and it is not necessary to suppose that such an event occurred in order to a correct understanding of the passage. All that is needful is to regard this as a representation of the mighty interposition of God; to suppose that his intervention was as direct, as manifest, and as sublime, as if he had thus interposed. There are frequent references in the Scriptures to such storms and tempests as illustrative of the majesty, the power, and the glory of God, and of the manner in which he interposes on behalf of his people. See Psalms 144:5; Psalms 46:6; Psalms 29:1; Job 37:21; Job 38:1; Nahum 1:3; and particularly Habakkuk 3:3. The description in Habakkuk strongly resembles the passage before us, and both were drawn doubtless from an actual observation of the fury of a tempest.

The foundations also of the hills moved - The mountains seemed to rock on their foundations. In the corresponding place in 2 Samuel 22:8 the expression is, “The foundations of heaven moved and shook;” that is, that on which the heavens seem to rest was agitated. Many suppose that the expression refers to the mountains as if they bore up the heavens; but DeWette more properly supposes that the reference is to the heavens as a building or an edifice resting on foundations. Why the change was made in revising the psalm from the “foundations of the heavens” to the “foundations of the hills,” it is impossible now to determine.

Because he was wroth - literally,” Because it was inflamed (or enkindled) to him;” that is, because he was angry. Anger is often compared to a raging flame, because it seems to consume everything before it. Hence, we speak of it as “heated,” as “burning.” So we say of one that he is “inflamed by passion.” The expression here is sublime in the highest degree. God seemed to be angry, and hence, he came forth in this awful manner, and the very earth trembled before him.