13 What then follows? “Be still.” To what purpose? “And see that I am God”. That is, Not ye, but I am God. I created, I create anew; I formed, I form anew; I made, I make anew. If you could not make yourself, how can you make yourself anew? This sees not the contentious tumult of man's soul; to which contentious tumult is it said, “Be still.” That is, restrain your souls from contradiction. Do not argue, and, as it were, arm against God. Else yet live your arms, not yet burned up with fire.
But if they are burned, “Be still;” because you have not wherewith to fight. But if you be still in yourselves, and from Me seek all, who before presumed on yourselves, then shall you “see that I am God.” “I will be exalted among the heathen, I will be exalted in the earth.” Just before I said, by the name of earth is signified the nation of the Jews, by the name of sea the other nations. The mountains were carried into the heart of the sea; the nations are troubled, the kingdoms are bowed; the Most High gave His Voice, and the earth was moved.
“The Lord of Hosts is with us, the God of Jacob is our taker up”. Miracles are done among the heathen, full filled is the faith of the heathen; burned are the arms of human presumption. Still are they, in tranquillity of heart, to acknowledge God the Author of all their gifts. And after this glorifying, does He yet desert the people of the Jews? Of which says the Apostle, “I say unto you, lest ye should be wise in your own conceits; that blindness in part is happened unto Israel, until the fullness of the Gentiles be come in.” That is, until the mountains be carried hither, the clouds rain here, the Lord here bows the kingdoms with His thunder, “until the fullness of the Gentiles be come in.”
And what thereafter? “And so all Israel shall be saved.” Therefore, here too observing the same order, “I will be exalted” (says He) “among the heathen, I will be exalted in the earth;” that is, both in the sea, and in the earth, that now might all say what follows: “the God of Jacob is our taker up.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)