Ps 103:32

“"Who looks on the earth, and makes it tremble; who touches the hills, and they shall smoke" [Psalm 104:32]. O earth, you were exulting in your good, to yourself you ascribed your fullness and opulence; behold, the Lord looks on you, and causes you to tremble. May He look on you, and make you tremble: for the trembling of humility is better than the confidence of pride....For it is God, he says, which works in you. For this reason then with trembling, because God works in you. Because He gave, because what you have comes not from you, you shall work with fear and trembling, for if you fear not Him, He will take away what He gave. Work, therefore, with trembling. Hear another Psalm: "Serve the Lord with fear, and rejoice unto Him with trembling." If we must rejoice with trembling, God beholds us, there comes an earthquake; when God looks upon us, let our hearts tremble; then will God rest there. Hear Him in another passage: "Upon whom shall My Spirit rest? Even on him that is lowly and quiet, and who trembles at My Word." [Isaiah 66:2] "Who looks on the earth, and makes it tremble; who touches the hills, and they shall smoke" [Psalm 104:32]. The hills were proud, and boastful of themselves, God had not touched them: He touches them, and they shall smoke. What means the smoking of the hills? That they pray unto the Lord. Behold great hills, proud hills, vast hills, prayed not to God: they wished themselves to be entreated, and entreated not Him who was above them. For what powerful, arrogant, proud man is there upon the earth, who deigns humbly to entreat God? I speak of the ungodly, not of the "cedars of Libanus, which the Lord has planted." Every ungodly man, unhappy soul, knows not how to entreat God, while he wishes himself to be entreated by men. He is a hill; it is needful that God touch him, that he may smoke: when he has begun to smoke, he will offer prayers unto God, as it were the sacrifice of his heart. He smokes unto God, he then beats his breast: he begins to weep, for smoke does elicit tears.”

“And the Prophet said, "He rebuketh the sea, and maketh it dry, and drieth up all the rivers;" and again, "He looketh on the earth and it trembleth; He rebuketh the mountains, and they smoke." And again the prophet Isaiah saith, "All the nations are accounted as nothing by Him." Now these things the Spirit of God spake concerning the power of God, that those things which were not He called to come into existence, and that what did exist He called and changed into nothing. To this power also He compareth faith.”

“"He looketh upon the earth, and it trembleth, He rebuketh the mountains, and they smoke." And again [the Book] saith, "At Thy rebuke they flee, and at the voice of Thy thunders they are afraid." And behold, according to the word of the Prophet, the fear of the Creator also resteth upon the natures which are speechless, because each of them is bound naturally to be afraid of Him; and if dumb things fear Him, how much more should intelligent beings fear Him?”

“On that verse of the Psalm: "He who looks upon the earth and makes it tremble," the Gloss says: "Then God looks upon the earth and makes it tremble, when he illumines the earthly man by the regard of his grace and converts him to his original principle, through which all things are begun and governed. And then man trembles." Therefore man ought greatly to consider what he thinks, what he speaks, and what he does, because God sees all things.”