9 For when he had said, “We have received Your mercy in the midst of Your people,” he signified that there is a people not receiving the mercy of God, in the midst of whom some do receive the mercy of God: and then lest it should occur to men that there are so few, as to be nearly none, how did He console them in the words following? “According to Your Name, O God, so is Your praise unto the ends of the earth”. What is this?...That is, as You are known through all the earth, so You are also praised through all the earth, nor are there wanting who now praise You through all the earth. But they praise You who live well. For, “According to Your Name, O God, so is Your praise,” not in a part, but “unto the ends of the earth.” “Your right hand is full of righteousness.” That is, many are they also who shall stand at Your right hand. Not only shall they be many who shall stand at Your left hand, but there also shall be a full heap set at Your right hand.
10. “Let mount Zion rejoice, and the daughters of Judah be glad, because of Your judgments, O Lord”. O mount Zion, O daughters of Judah, you labour now among tares, among chaff, among thorns ye labour: yet be glad because of God's judgments. God errs not in judgment. Live ye separate, though separate you were not born; not vainly has a voice gone forth from your mouth and heart, “Destroy not my soul with sinners, nor my life with bloody men.” He shall winnow with such art, carrying in His hand a fan, that not one grain of wheat shall fall into the heap of chaff prepared to be burned, nor one beard of chaff pass to the heap to be laid up in the garner. Be glad, O you daughters of Judæa, because of the judgments of God that errs not, and do not yet judge rashly. To you let it belong to collect, to Him let it belong to separate. But think not that the “daughters of Judah” are Jews. Judah is confession; all the sons of confession are all the sons of Judah. For “salvation is of the Jews,” is nothing else than that Christ is of the Jews. This says also the Apostle, “He is not a Jew which is one outwardly; neither is that circumcision which is outward in the flesh: but he is a Jew which is one inwardly, and circumcision is that of the heart, in the spirit, and not in the letter, whose praise is not of men, but of God.” Be such a Jew; glory in the circumcision of the heart, though you have not the circumcision of the flesh. Let the daughters of Judah be glad, because of Your judgments, O Lord.
11. “Walk about Zion, and embrace her”. Be it said to them who live ill, in the midst of whom is the people, which has received the mercy of God. In the midst of you is a people living well, “Walk about Zion.” But how? “embrace her.” Not with scandals, but with love go round about her: that so those who live well in the midst of you ye may imitate, and by imitation of them, be incorporate with Christ, whose members they are. “Walk about Zion, go round about her: speak in the towers thereof.” In the height of her bulwarks, set forth the praises thereof.
12. “Set your hearts upon her might”. Not that you may have the form of godliness, deny the power thereof, but, “upon her might set your hearts. Speak ye in her towers.” What is the might of this city? Whoso would understand the might of this city, let him understand the force of love. That is a virtue which none conquers. Love's flame no waves of the world, no streams of temptation, extinguish. Of this it is said, “Love is strong as death.” For as when death comes, it cannot be resisted; by whatever arts, whatever medicines, you meet it; the violence of death can none avoid who is born mortal; so against the violence of love can the world do nothing. For from the contrary the similitude is made of death; for as death is most violent to take away, so love is most violent to save. Through love many have died to the world, to live to God; by this love inflamed, the martyrs, not pretenders, not puffed up by vain-glory, not such as they of whom it is written, “Though I give my body to be burned, and have not charity, it profits me nothing,” but men whom truly a love of Christ and of the truth led on to this passion; what to them were the temptations of the tormentors? Greater violence had the eyes of their weeping friends, than the persecutions of enemies. For how many were held by their children, that they might not suffer? To how many did their wives fall upon their knees, that they might not be left widows? How many have their parents forbidden to die; as we know and read in the Passion of the Blessed Perpetua! All this was done; but tears, however great, and with whatever force flowing, when did they extinguish the ardour of love? This is the might of Sion, to whom elsewhere it is said, “Peace be within your walls, and prosperity within your palaces.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)