10 Commending this to the ears of God, let him say, “Lord, Lord.” Thou Lord-Lord, that is, most truly Lord, not like the lords-men, not like the lords who buy with money-bags, but the Lord who buys with His Blood. “Lord, Lord, Thou strength of my health”, that is, who givest strength to my health. What is the meaning of “strength of my health”? He complained of the stumbling-blocks and snares of sinners, of wicked men, vessels of the devil, that barked around him and laid snares around him, of the proud that envy the righteous. But He immediately added a comfort, “He that shall endure unto the end, the same shall be saved.” This he observed and feared, and, distressed at the abundance of iniquities, turned himself to hope. Verily I shall be saved, if I endure unto the end: but endurance, so as to win salvation, pertains unto strength; You are “the strength of my salvation;” You make me to endure, that I may attain salvation....Toiling then in this warfare, he looked back to the grace of God; and because already he had begun to be heated and parched, he found, as it were, a shade, whereunder to live. “You have overshadowed my head in the day of battle:” that is, in the heat, lest I be heated, lest I be parched.
11. “Deliver me not over, O Lord, by my own longing to the sinner”. Behold to what end Your overshadowing shall avail for me, that I suffer not heat from myself. And what could that “sinner” do to me, rage as he would? For wicked men raged against the martyrs, dragged them away, bound them with chains, shut them up in prisons, slew them with the sword, exposed them to wild beasts, consumed them with fire: all this they did; yet did not God deliver them over to the sinners, because they were not delivered over by their own longing. This then pray with all your might, that God “delivered you not over by your own longing to the sinner.” For thou by your own longing givest place to the devil. For lo, the devil has set before you gain, invited you to dishonesty; you can not have the gain, unless thou commit the dishonesty: the gain is the bait, dishonesty the snare: do thou so look on the bait, that you see the snare also; for you can not obtain the gain, unless thou commit the dishonesty; and if you commit the dishonesty, you will be caught....Hence is your head overshadowed in the day of battle. For longing causes heat, but the overshadowing of the Lord tempers longing, that we may be able to bridle that whereby we were being hurried away, that we be not so heated as to be drawn to the snare. “They have thought against me; leave me not, lest perchance they be exalted.” You have in another place, “They that oppress me will exult if I be moved.” Such are they, because such is the devil also himself....
12. “The head of their going about, the toil of their own lips shall cover them”. Me, he says, the shadow of Your wings shall cover: for, “You have covered me in the day of battle.” Them what shall cover? “The head of their going about;” that is, pride. What is, “their going about”? How they go about and stand not, how they go in the circle of error, where is journeying without end. He who goes in a straight line, begins from some point, ends at some point: he who goes in a circle, never ends. That is the toil of the wicked, which is set forth yet more plainly in another Psalm, “The wicked walk in a circle.” But “the head of their going about” is pride, for pride is the beginning of every sin. But whence is pride “the toil of their own lips”? Every proud man is false, and every false man is a liar. Men toil in speaking falsehood; for truth they could speak with entire facility. For he toils, who makes what he says: he who wishes to speak the truth, toils not, for truth herself speaks without toil....
13. “Coals of fire shall fall upon them upon earth, and You shall cast them down”. What is, “upon earth”? Here, even in this life, here “coals of fire shall fall upon them.” What are, “coals of fire”? We know these coals. Are they different from those of which we are about to speak? For these I see avail for punishment, those that I am about to speak of, for salvation. For we have spoken of certain coals, when man was seeking aid against a treacherous tongue....The examples of the “coals” are added to the wound of the arrows (for I need not fear to say “the wound,” when the Spouse herself says, “I am wounded with love”), and then the hay is consumed, and so they are called “devouring coals.” The hay is devoured, but the gold is purified, and the man exchanges death for life, and begins to be himself too a burning coal; such a coal as was the Apostle, “who before was a blasphemer and a persecutor and injurious,” a coal black and extinguished; but when he had obtained mercy, he was set on fire from heaven, the voice of Christ set him on fire, all the blackness in him perished, he began to be fervent in spirit, to set others on fire with that wherewith he was set on fire himself....
14. “A man full of words shall not be guided upon earth”. “A man full of words” loves lies. For what pleasure has he, save in speaking? He cares not what he speaks, so long as he speaks. It cannot be that he will be guided. What then ought the servant of God to do, who is kindled with these “coals,” and himself made a coal of salvation, what should he do? He should wish rather to hear than to speak; as it is written, “Let every man be swift to hear, slow to speak.” And if it may be so, let him desire this, not to be obliged to speak and talk and teach....I can quickly tell you wherein each one may prove himself, not by never speaking, but by requiring a case where it is his duty to speak; let him be glad to be silent, in will, let him speak to teach, when he must. For when must thou needs speak and teach? When you meet with one ignorant, when you meet with one unlearned. If it delight you always to teach, you wish always to have some ignorant one to teach....“Evil shall hunt the unrighteous man to destruction.” Evils come, and he stands not; therefore said he, “they shall hunt him to destruction.” For many good men, many righteous men evils have befallen, evils have, as it were, found them. Therefore when the evil pursued the good, that is, our martyrs, when they seized them, they “hunted” them, but not “to destruction.” For the flesh was pressed down, the spirit was crowned; the spirit was cast out from the body, yet was nought done to the flesh which might hinder it for the future. Let the flesh be burned, scourged, mangled; is it therefore withdrawn from its Creator, because it is given into the hands of its persecutor? Will not He who created it from nothing, remake it better than it was?
15. “I know that the Lord will maintain the right of the needy”. This “needy” one is not “full of words;” for he that is full of words, wishes to abound, knows not to hunger. He is “needy” of whom it is said, “Blessed are they which do hunger and thirst after righteousness, for they shall be filled.” They groan among the stumbling-blocks of the wicked, they pray to their Head, to be delivered from the wicked man. “And the cause of the poor.” These then are they whose cause the Lord will not neglect; although now they suffer hardships, their glory shall appear, when their Head appears. For to such while placed here it is said, “You are dead, and your life is hid with Christ in God.” So then we are poor, our life is hid; let us cry to Him that is our Bread....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)