1 This Psalm has on the title the inscription, “For the end, a song of a Psalm of Resurrection.” When ye hear “for the end,” whenever the Psalms are repeated, understand it “for Christ:” the Apostle saying, “For the end of the law is Christ, for righteousness to every one believing.” In what manner therefore here Resurrection is sung, you wilt hear, and whose Resurrection it is, as far as Himself deigns to give and disclose. For the Resurrection we Christians know already has come to pass in our Head, and in the members it is to be. The Head of the Church is Christ, the members of Christ are the Church. That which has preceded in the Head, will follow in the Body. This is our hope; for this we believe, for this we endure and persevere amid so great perverseness of this world, hope comforting us, before that hope becomes reality....The Jews did hold the hope of the resurrection of the dead: and they hoped that themselves alone would rise again to a blessed life because of the work of the Law, and because of the justifications of the Scriptures, which the Jews alone had, and the Gentiles had not. Crucified was Christ, “blindness in part happened unto Israel, in order that the fullness of the Gentiles might enter in:” as the Apostle says. The resurrection of the dead begins to be promised to the Gentiles also that believe in Jesus Christ, that He has risen again. Thence this Psalm is against the presumption and pride of the Jews, for the comfort of the Gentiles that are to be called to the same hope of resurrection.
2....Thence he begins, “Be joyful in God.” Who? “Every land”. Not therefore Judæa alone. See, brethren, after what sort is set forth the universality of the Church in the whole world spread abroad: and mourn ye not only the Jews, who envied the Gentiles that grace, but still more for heretics wail ye. For if they are to be mourned, that have not been gathered together, how much more they that being gathered together have been divided? “Jubilate in God every land.” What is “jubilate”? Into the voice of rejoicings break forth if you cannot into that of words. For “jubilation” is not of words, but the sound alone of men rejoicing is uttered, as of a heart labouring and bringing forth into voice the pleasure of a thing imagined which cannot be expressed. “Be joyful in God every land:” let no one jubilate in a part: let every land be joyful, let the Catholic Church jubilate. The Catholic Church embraces the whole: whosoever holds a part and from the whole is cut off, should howl, not jubilate.
3. “But play ye to His name”. What has he said? By you “playing” let His name be blessed. But what it is to “play”? To play is also to take up an instrument which is called a psaltery, and by the striking and action of the hands to accompany voices. If therefore ye jubilate so that God may hear; play also something that men may both see and hear: but not to your own name....For if for the sake of yourselves being glorified ye do good works, we make the same reply as He made to certain of such men, “Verily I say unto you, they have received their reward:” and again, “Otherwise no reward ye will have with your Father that is in Heaven.” You will say, ought I, then, to hide my works, that I do them not before men? No. But what says He? “Let your works shine before men.” In doubt then I shall remain. On one side You say to me, “Take heed that you do not your righteousness before men:” on the other side You say to me, “Let your good works shine before men;” what shall I keep? What do? What leave undone? A man can as well serve two masters commanding different things as one commanding different things. I command not, says the Lord, different things. The end observe, for the end sing: with what end you do it, see thou. If for this reason you do it, that you may be glorified, I have forbidden it: but if for this reason, that God may be glorified, I have commanded it. Play therefore, not to your own name, but to the name of the Lord your God. Play ye, let Him be lauded: live ye well, let Him be glorified. For whence have ye that same living well? If for everlasting ye had had it, you would never have lived ill; if from yourselves ye had had it, you never would have done otherwise than have lived well. “Give glory to His praise.” Our whole attention upon the praise of God he directs, nothing for us he leaves whence we should be praised. Let us glory thence the more, and rejoice: to Him let us cleave, in Him let us be praised. You heard when the Apostle was being read, “See ye your calling, brethren, how not many wise after the flesh, not many mighty, not many noble, but the foolish things of the world God has chosen to confound the wise.”...But the Lord chose afterwards orators also; but they would have been proud, if He had not first chosen fishermen; He chose rich men; but they would have said that on account of their riches they had been chosen, unless at first He had chosen poor men: He chose Emperors afterwards; but better is it, that when an Emperor has come to Rome, he should lay aside his crown, and weep at the monument of a fisherman, than that a fisherman should weep at the monument of an Emperor. “For the weak things of the world God has chosen to confound the strong,” etc....And what follows? The Apostle has concluded, “That there might not glory before God any flesh.” See ye how from us He has taken away, that He might give glory: has taken away ours, that He might give His own; has taken away empty, that He might give full; has taken away insecure, that He might give solid....
4. “Say ye to God, How to be feared are Your works!”. Wherefore to be feared and not to be loved? Hear another voice of a Psalm: “Serve the Lord in fear, and exult unto Him with trembling.” What means this? Hear the voice of the Apostle: “With fear,” he says, “and trembling, work out your own salvation.” Wherefore with fear and trembling? He has subjoined the reason: “for God it is that works in you both to will and to work according to good will.” If therefore God works in you, by the Grace of God you work well, not by your strength. Therefore if you rejoice, fear also: lest perchance that which was given to a humble man be taken away from a proud one....Brethren, if against the Jews of old, cut off from the root of the Patriarchs, we ought not to exalt ourselves, but rather to fear and say to God, “How to be feared are Your works:” how much less ought we not to exalt ourselves against the fresh wounds of the cutting off! Before there had been cut off Jews, graffed in Gentiles; from the very graft there have been cut off heretics; but neither against them ought we to exalt ourselves; lest perchance he deserve to be cut off, that delights to revile them that are cut off. My brethren, a bishop's voice, however unworthy, has sounded to you: we pray you to beware, whosoever you are in the Church, do not revile them that are not within; but pray ye rather, that they too may be within. For God is able again to graft them in. Of the very Jews the Apostle said this, and it was done in their case. The Lord rose again, and many believed: they perceived not when they crucified, nevertheless afterwards they believed in Him, and there was forgiven them so great a transgression. The shedding of the Lord's blood was forgiven the manslayers, not to say, God-slayers: “for if they had known, the Lord of glory they never would have crucified.” Now to the manslayers has been forgiven the shedding of the blood of Him innocent: and that same blood which through madness they shed, through grace they have drunk....O fullness of Gentiles, say thou to God, “How to be feared are Your works!” and so rejoice thou as that you may fear, be not exalted above the branches cut off.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)