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1 Praise ye the LORD. Sing unto the LORD a new song, and his praise in the congregation of saints. 2 Let Israel rejoice in him that made him: let the children of Zion be joyful in their King. 3 Let them praise his name in the dance: let them sing praises unto him with the timbrel and harp. 4 For the LORD taketh pleasure in his people: he will beautify the meek with salvation. 5 Let the saints be joyful in glory: let them sing aloud upon their beds. 6 Let the high praises of God be in their mouth, and a twoedged sword in their hand; 7 To execute vengeance upon the heathen, and punishments upon the people; 8 To bind their kings with chains, and their nobles with fetters of iron; 9 To execute upon them the judgment written: this honour have all his saints. Praise ye the LORD.
[AD 430] Augustine of Hippo on Psalms 149:1
Let us praise the Lord both in voice, and in understanding, and in good works; and, as this Psalm exhorts, let us sing unto Him a new song. It begins: "Sing ye to the Lord a new song. His praise is in the Church of the Saints" [Psalm 149:1]. The old man has an old song, the new man a new song. The Old Testament is an old song, the New Testament a new song. In the Old Testament are temporal and earthly promises. Whoso loves earthly things sings an old song: let him that desires to sing a new song, love the things of eternity. Love itself is new and eternal; therefore is it ever new, because it never grows old....And this song is of peace, this song is of charity. Whoso severs himself from the union of the saints, sings not a new song; for he has followed old strife, not new charity. In new charity what is there? Peace, the bond of an holy society, a spiritual union, a building of living stones. Where is this? Not in one place, but throughout the whole world. This is said in another Psalm, "Sing unto the Lord, all the earth." From this is understood, that he who sings not with the whole earth, sings an old song, whatever words proceed out of his mouth....We have already said, brethren, that all the earth sings a new song. He who sings not with the whole earth a new song, let him sing what he will, let his tongue sound forth Halleluia, let him utter it all day and all night, my ears are not so much bent to hear the voice of the singer, but I seek the deeds of the doer. For I ask, and say, "What is it that you sing?" He answers, "Halleluia." What is "Halleluia"? "Praise ye the Lord." Come, let us praise the Lord together. If you praise the Lord, and I praise the Lord, why are we at variance? Charity praises the Lord, discord blasphemes the Lord....

[AD 430] Augustine of Hippo on Psalms 149:1-3
My brothers and sisters, my children, O seedlings of the catholic church, O holy and heavenly seed, O you that have been born again in Christ and been born from above, listen to me—or rather, listen to God through me: “Sing to the Lord a new song.” “Well, I am singing,” you say. Yes, you are singing, of course you are singing, I can hear you. But do not let your life give evidence against your tongue. Sing with your voices, sing also with your hearts; sing with your mouths, sing also with your conduct. “Sing to the Lord a new song.” You ask what you should sing about the one you love? For of course you do want to sing about the one you love. You are asking for praises of his to sing. You have been told, “Sing to the Lord a new song.” You are looking for songs of praise, are you? “His praise is in the church of the saints.” The praise of the one to be sung about is the singer himself. Do you want to sing God his praises? Be yourselves what you sing. You are his praise if you lead good lives.His praise, you see, is not to be found in the synagogues of the Jews, or in the madness of the pagans, or in the errors of the heretics or in the applause of the theaters. You ask, “Where it is to be found?” Look at yourselves: you are it. “His praise is in the church of the saints.” You ask what to rejoice about when you are singing? “Let Israel rejoice in the one who made him,” and all he can find to rejoice about is God.

[AD 585] Cassiodorus on Psalms 149:1-3
“Let them praise his name in the choir; let them play music for him on the timbrel and harp.” In an earlier verse he said that we must rejoice in the Lord Christ, but now he says that we must praise the name of the Lord in the choir. That is to say, in the choir that never suffers any scattering, boredom or scandal, but is gathered in the uprightness of merits and always exists with the dearest unity. But another psalm explains what this choir is like and how big it is: “From the rising of the sun to its setting, praise the name of the Lord.” The chorus that is gathered from the beginning of the world from the multitude of the heathen also cannot be gathered except in that heavenly homeland.

[AD 430] Augustine of Hippo on Psalms 149:2
"Let Israel rejoice in Him who made Him" [Psalm 149:2]. What is, "Israel"? "Seeing God." He who sees God, rejoices in Him by whom he was made. What is it then, brethren? We have said that we belong to the Church of the saints: do we already see God? And how are we Israel, if we see not? There is one kind of sight belonging to this present time; there will be another belonging to the time hereafter: the sight which now is, is by faith; the sight which is to be will be in reality. If we believe, we see; if we love, we see: see what? God. Ask John: "God is love;" [1 John 4:16] let us bless His holy Name, and rejoice in God by rejoicing in love. Whoso has love, why send we him afar to see God? Let him regard his own conscience, and there he sees God...."And let the sons of Sion exult in their King." The sons of the Church are Israel. For Sion indeed was one city, which fell: amid its ruins certain saints dwelt after the flesh: but the true Sion, the true Jerusalem (for Sion and Jerusalem are one), is "eternal in the heavens," [2 Corinthians 5:1] and is "our mother." [Galatians 4:26] She it is that has given us birth, she is the Church of the saints, she has nourished us, she, who is in part a pilgrim, in part abiding in the heavens. In the part which abides in heaven is the bliss of angels, in the part which wanders in this world is the hope of the righteous. Of the former is said, "Glory to God in the highest;" of the latter, "and on earth peace to men of good will." [Luke 2:14] Let those then who, being in this life, groan, and long for their country, run by love, not by bodily feet; let them seek not ships but wings, let them lay hold on the two wings of love. What are the two wings of love? The love of God, and of our neighbour. For now we are pilgrims, we sigh, we groan. There has come to us a letter from our country: we read it to you. "And the sons of Sion shall exult in their King." The Son of God, who made us, was made one of us: and He rules us as our King, because He is our Creator, who made us. But He by whom we were made is the same as He by whom we are ruled, and we are Christians because He is Christ. He is called Christ from Chrism, that is, Anointing....Give to the Priest somewhat to offer. What could man find which he could give as a clean victim? What victim? What clean thing can a sinner offer? O unrighteous, O sinful man, whatever you offer is unclean, and somewhat that is clean must be offered for you....Let then the Priest that is clean offer Himself, and cleanse you. This is what Christ did. He found in man nothing clean for Him to offer for man: He offered Himself as a clean Victim. Happy Victim, true Victim, spotless Offering. He offered not then what we gave Him; yea rather, He offered what He took of us, and offered it clean. For of us He took flesh, and this He offered. But where took He it? In the womb of the Virgin Mary, that He might offer it clean for us unclean. He is our King, He is our Priest, in Him let us rejoice.

[AD 430] Augustine of Hippo on Psalms 149:3
"Let them praise His Name in chorus" [Psalm 149:3]. What means "chorus"? Many know what a "chorus" is: nay, as we are speaking in a town, almost all know. A "chorus" is the union of singers. If we sing "in chorus," let us sing in concord. If any one's voice is out of harmony in a chorus of singers, it offends the ear, and throwes the chorus into confusion. If the voice of one echoing discordantly troubles the harmony of them who sing, how does the discord of heresy throw into confusion the harmony of them who praise. The whole world is now the chorus of Christ. The chorus of Christ sounds harmoniously from east to west. "Let them sing a psalm unto Him with timbrel and psaltery." Wherefore takes he to him the "timbrel and psaltery"? That not the voice alone may praise, but the works too. When timbrel and psaltery are taken, the hands harmonize with the voice. So too do thou, whenever you sing, "Halleluia," deal forth your bread to the hungry, clothe the naked, take in the stranger: then does not only your voice sound, but your hand sounds in harmony with it, for your deeds agree with your words. You have taken to you an instrument, and your fingers agree with your tongue. Nor must we keep back the mystical meaning of the "timbrel and psaltery." On the timbrel leather is stretched, on the psaltery gut is stretched; on either instrument the flesh is crucified. How well did he "sing a psalm on timbrel and psaltery," who said, "the world is crucified unto me, and I unto the world"? [Galatians 6:14] This psaltery or timbrel He wishes you to take up, who loves a new song, who teaches you, saying to you, "Whosoever wills to be My disciple, let him deny himself, and take up his cross, and follow Me." [Matthew 16:24] Let him not set down his psaltery, let him not set down his timbrel, let him stretch himself out on the wood, and be dried from the lust of the flesh. The more the strings are stretched, the more sharply do they sound. The Apostle Paul then, in order that his psaltery might sound sharply, what said he? "Stretching forth unto those things which are before," etc. [Philippians 3:13] He stretched himself: Christ touched him; and the sweetness of truth sounded.

[AD 430] Augustine of Hippo on Psalms 149:4
"For the Lord has dealt kindly among His people" [Psalm 149:4]. What dealing so kindly, as to die for the ungodly? What dealing so kindly, as with righteous Blood to blot out the handwriting against the sinner? What dealing so kindly, as to say, "I regard not what you were, be ye now what you were not"? He deals kindly in converting him that was turned away, in aiding him that is fighting, in crowning the conqueror. "And the meek He shall lift up in salvation." For the proud too are lifted up, but not in salvation: the meek are lifted in salvation, the proud in death: that is, the proud lift up themselves, and God humbles them: the meek humble themselves, and God lifts them up.

[AD 430] Augustine of Hippo on Psalms 149:5
"The saints shall exult in glory" [Psalm 149:5]. I would say somewhat important about the glory of the saints. For there is no one who loves not glory. But the glory of fools, popular glory as it is called, has snares to deceive, so that a man, influenced by the praises of vain men, shall be willing to live in such fashion as to be spoken of by men, whosoever they be, in whatsoever way. Hence it is that men, rendered mad, and puffed up with pride, empty within, without swollen, are willing ever to ruin their fortunes by bestowing them on stage-players, actors, men who fight with wild beasts, charioteers. What sums they give, what sums they spend! They lavish the powers not only of their patrimony, but of their minds too. They scorn the poor, because the people shouts not that the poor should be given to, but the people do shout that the fighter with wild beasts be given to. When then no shout is raised to them, they refuse to spend; when madmen shout to them, they are mad too: nay, all are mad, both performer, and spectator, and the giver. This mad glory is blamed by the Lord, is offensive in the eyes of the Almighty....Thou choosest to clothe the fighter with wild beasts, who may be beaten, and make you blush: Christ is never conquered; He has conquered the devil, He has conquered for you, and to you, and in you; such a conqueror as this you choose not to clothe. Wherefore? Because there is less shouting, less madness about it. They then who delight in such glory, have an empty conscience. Just as they drain their chests, to send garments as presents, so do they empty their conscience, so as to have nothing precious therein.

[AD 604] Gregory the Dialogist on Psalms 149:5
It is said in the psalm regarding just individuals: “The saints will rejoice exceedingly in glory; they will rejoice in their beds”; because when they flee evils from the outside, they glory secure within the secret recesses of their minds. Then the joys of their hearts will have been fulfilled when there will have been no external struggles with the flesh. For until the flesh is subdued, one’s bed is disturbed just as the wall of our house shakes.

[AD 430] Augustine of Hippo on Psalms 149:6
But the saints who "exult in glory," no need is there for us to say how they exult: just hear the verse of the Psalm which follows: "The saints shall exult in glory, they shall rejoice in their beds:" not in theatres, or amphitheatres, or circuses, or follies, or market places, but "in their chambers." What is, "in their chambers"? In their hearts. Hear the Apostle Paul exulting in his closet: "For this is our glory, the testimony of our conscience." [2 Corinthians 1:12] On the other hand, there is reason to fear lest any be pleasing to himself, and so seem to be proud, and boast of his conscience. For every one ought to exult with fear, for that wherein he exults is God's gift, not his own desert. For there be many that please themselves, and think themselves righteous; and there is another passage which goes against them, which says, "Who shall boast that he has a clean heart, and that he is pure from sin?" [Proverbs 20:9] There is then, so to speak, a limit to glorying in our conscience, namely, to know that your faith is sincere, your hope sure, your love without dissimulation. "The exultations of God are in their mouths" [Psalm 149:6]. In such wise shall they "rejoice in their closets," as not to attribute to themselves that they are good, but praise Him from whom they have what they are, by whom they are called to attain to what they are not, and from whom they hope for perfection, to whom they give thanks, because He has begun.

[AD 430] Augustine of Hippo on Psalms 149:8-9
"That they may bind their kings in fetters, and their nobles in bonds of iron" [Psalm 149:8]. "To execute upon them the judgment written" [Psalm 149:9]. 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." [Matthew 19:21] 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," [Sirach 6:25] 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." [1 John 4:18] 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." [Sirach 6:24] ...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." [Matthew 5:32] 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." [Matthew 19:6] 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." [Matthew 19:10] 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." [Matthew 19:11-12] "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.