9 Now, brethren, you see the saints armed: observe the slaughter, observe their glorious battles. For if there be a commander, there must be soldiers; if soldiers, an enemy; if a warfare, a victory. What have these done who had in their hands swords sharpened on both sides? “To do vengeance on the nations.” See whether vengeance have not been done on the nations. Daily is it done: we do it ourselves by speaking. Observe how the nations of Babylon are slain. She is repaid twofold: for so is it written of her, “repay her double for what she has done.” How is she repaid double? The saints wage war, they draw their “swords twice sharpened;” thence come defeats, slaughters, severances: how is she repaid double? When she had power to persecute the Christians, she slew the flesh indeed, but she crushed not God: now she is repaid double, for the Pagans are extinguished and the idols are broken....And lest you should think that men are really smitten with the sword, blood really shed, wounds made in the flesh, he goes on and explains, “upbraidings among the peoples.” What is “upbraidings”? Reproof. Let the “sword twice sharpened” go forth from you, delay not. Say to your friend, if yet you have one left to whom to say it, “What kind of man are you, who hast abandoned Him by whom you were made, and worshippest what He made? Better is the Workman, than that which He works.” When he begins to blush, when he begins to feel compunction, you have made a wound with your sword, it has reached the heart, he is about to die, that he may live.
10. “That they may bind their kings in fetters, and their nobles in bonds of iron”. “To execute upon them the judgment written”. The kings of the Gentiles are to be bound in fetters, “and their nobles in fetters,” and that “of iron.”...For these verses which we are beginning to explain are obscure. For for this purpose God willed to set down some of His verses obscurely, not that anything new should be dug out of them, but that what was already well known, might be made new by being obscurely set forth. We know that kings have been made Christians; we know that the nobles of the Gentiles have been made Christians. They are being made so at this day; they have been, they shall be; the “swords twice sharpened” are not idle in the hands of the saints. How then do we understand their being bound in fetters and chains of iron? You know, beloved and learned brethren (learned I call you, for you have been nourished in the Church, and are accustomed to hear God's Word read), that “God has chosen the weak things of the world to confound the strong, and the foolish things of the world has God chosen to confound the wise, and things which are not, just as things which are, that the things which are may be brought to nought.”...It is said by the Lord, “If you will be perfect, go sell all that you have, and give to the poor, and come, follow Me, and you shall have treasure in heaven.” Many of the nobles did this, but they ceased to be nobles of the Gentiles, they chose rather to be poor in this world, noble in Christ. But many retain their former nobility, retain their royal powers, and yet are Christians. These are, as it were, “in fetters and in bonds of iron.” How so? They received fetters, to keep them from going to things unlawful, the “fetters of wisdom,” the fetters of the Word of God. Wherefore then are they bonds of iron and not bonds of gold? They are iron so long as they fear: let them love, and they shall be golden. Observe, beloved, what I say. You have heard just now the Apostle John, “There is no fear in love, but perfect love casts out fear, because fear has torment.” This is the bond of iron. And yet unless a man begin through fear to worship God, he will not attain to love. “The fear of the Lord is the beginning of wisdom.” The beginning then is bonds of iron, the end a collar of gold. For it is said of wisdom, “a collar of gold around your neck.”...There comes to us a man powerful in this world, his wife offends him, and perhaps he has desired another man's wife who is more beautiful, or another woman who is richer, he wishes to put away the one he has, yet he does it not. He hears the words of the servant of God, he hears the Prophet, he hears the Apostle, and he does it not; he is told by one in whose hands is a “sword twice sharpened,” You shall not do it: it is not lawful for you: God allows you not to put away your wife, “save for the cause of fornication.” He hears this, he fears, and does it not....Listen, young men; the bonds are of iron, seek not to set your feet within them; if you do, you shall be bound more tightly with fetters. Such fetters the hands of the Bishop make strong for you. Do not men who are thus fettered fly to the Church, and are here loosed? Men do fly hither, desiring to be rid of their wives: here they are more tightly bound: no man looses these fetters. “What God joined together, let not man put asunder.” But these bonds are hard. Who but knows it? This hardness the Apostles grieved at, and said, “If this be the case with a wife, it is not good to marry.” If the bonds be of iron, it is not good to set our feet within them. And the Lord said, “All men cannot receive this saying, but let him that can receive it, receive it.” “Are you bound unto a wife? Seek not to be freed,” for you are bound with bonds of iron. “Are you free from a wife, seek not a wife;” bind not yourself with bonds of iron.
11. “To do in them the judgment that is written.” This is the judgment which the saints do throughout all nations. Wherefore “written”? Because these things were before written, and now are fulfilled. Behold now they are being done: erst they were read, and were not done. And he has concluded thus, “this glory have all His saints.” Throughout the whole world, throughout entire nations, this the saints do, thus are they glorified, thus do they “exalt God with their mouths,” thus do they “rejoice in their beds,” thus do they “exult in their glory,” thus are they “lifted up in salvation,” thus do they “sing a new song,” thus in heart and voice and life they say Halleluia. Amen.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)