1 O sing unto the LORD a new song; for he hath done marvellous things: his right hand, and his holy arm, hath gotten him the victory. 2 The LORD hath made known his salvation: his righteousness hath he openly shewed in the sight of the heathen. 3 He hath remembered his mercy and his truth toward the house of Israel: all the ends of the earth have seen the salvation of our God. 4 Make a joyful noise unto the LORD, all the earth: make a loud noise, and rejoice, and sing praise. 5 Sing unto the LORD with the harp; with the harp, and the voice of a psalm. 6 With trumpets and sound of cornet make a joyful noise before the LORD, the King. 7 Let the sea roar, and the fulness thereof; the world, and they that dwell therein. 8 Let the floods clap their hands: let the hills be joyful together 9 Before the LORD; for he cometh to judge the earth: with righteousness shall he judge the world, and the people with equity.
[AD 339] Eusebius of Caesarea on Psalms 98:1-4
Along with my prayers I now add book 10 to the Church History and dedicate it to you, my most consecrated Paulinus, and blazon you as the seal of the whole work. It is appropriate that in a perfect number2 I shall here provide a completed account in celebration of the restoration of the churches, in obedience to the divine Spirit who urges us:

Sing to the Lord a new song, for he has done marvelous things;
His right and his holy arm have wrought salvation for him.
The Lord has made known his salvation:
His righteousness he has revealed in the sight of the heathen.

Accordingly, let me now sing the new song, since after those grim and horrifying scenes and narratives, I was now privileged to see and to celebrate what many righteous people and martyrs of God before me desired to see but did not see and to hear but did not hear. But they hurried on to far better things in the heavens, caught up into a paradise of divine bliss, while I, admitting that even the present circumstances are more than I deserve, have been totally astonished at the magnitude of grace he has conferred and offer him my total awe and worship, confirming the truth of the prophecies that declare:

Come and behold the works of the Lord,
What wonders he has wrought on the earth,
Making wars to cease to the ends of the world.
He will break the bow and shatter the spear,
And the shields he will burn with fire.

Rejoicing that all this has been clearly fulfilled, let me proceed with my narrative.

[AD 430] Augustine of Hippo on Psalms 98:1
"O sing unto the Lord a new song" [Psalm 98:1]. The new man knows this, the old man knows it not. The old man is the old life, and the new man the new life: the old life is derived from Adam, the new life is formed in Christ. But in this Psalm, the whole world is enjoined to sing a new song. More openly elsewhere the words are these: "O sing unto the Lord a new song; sing unto the Lord, all the whole earth;" that they who cut themselves off from the communion of the whole earth, may understand that they cannot sing the new song, because it is sung in the whole, and not in a part of it. Attend here also, and see that this is said. And when the whole earth is enjoined to sing a new song, it is meant, that peace sings a new song. "For He has done marvelous things." What marvelous things? Behold, the Gospel was just now being read, and we heard the marvellous things of the Lord. The only son of his mother, who was a widow, was being carried out dead: the Lord, in compassion, made them stand still; they laid him down, and the Lord said, "Young man, I say unto you, Arise." [Luke 7:12-14] ..."The Lord has done marvellous things." What marvellous things? Hear: "His own right hand, and His holy arm, has healed for Him." What is the Lord's holy Arm? Our Lord Jesus Christ. Hear Isaiah: "Who has believed our report, and to whom is the arm of the Lord revealed?" [Isaiah 53:1] His holy arm then, and His own right hand, is Himself. Our Lord Jesus Christ is therefore the arm of God, and the right hand of God; for this reason is it said, "has He healed for Him." It is not said only, "His right hand has healed the world," but "has healed for Him." For many are healed for themselves, not for Him. Behold how many long for that bodily health, and receive it from Him: they are healed by Him, but not for Him. How are they healed by Him, and not for Him? When they have received health, they become wanton: they who when sick were chaste, when cured become adulterers: they who when in illness injured no man, on the recovery of their strength attack and crush the innocent: they are healed, but not unto Him. Who is he who is healed unto Him? He who is healed inwardly. Who is he that is healed inwardly? He who trusts in Him, that when he shall have been healed inwardly, reformed into a new man, afterwards this mortal flesh too, which does languish for a time, may in the end itself even recover its most perfect health. Let us therefore be healed for Him. But that we may be healed for Him, let us believe in His right hand.

[AD 450] Peter Chrysologus on Psalms 98:1-4
“Sing joyfully to God, all the earth.” What is it that an understanding of this great joy is likely to make clear? Why is it that, after God gave commandments so great, so terrifying and so awesome, he now invites the earth to a shout of joy? “Sing joyfully to God, all the earth,” the text reads.What other reason is there than the following? The awesome God later on chose the role of a very gentle shepherd. He assumed this character in order to act as a merciful shepherd and gather together, like straggling sheep into one fold, those wandering peoples, those straying nations, those tribes scattered far and wide. Yes, more, he wanted to lead back to the use of milk and grass and restore those wild nations that were languishing after the prey of a carcass, the eating of flesh, the drinking of blood and the fury of beasts. Briefly, he desired to make them once more truly humble sheep.
“All the earth sing joyfully to God,” he says, and by this command he imposes his shepherdly control on all the earth. The resounding trumpet draws the soldier forth to war; just so does the sweetness of this jubilant call invite the sheep to pasture. How fitting it was to mitigate the din of fighting by shepherdly kindness, in order that such gentle grace might save the nations that their own natural wildness had long been destroying.

[AD 585] Cassiodorus on Psalms 98:1-4
The phrase “Sing and exult and play the lyre” follows. Although these words seem to be similar, nonetheless they are separated by some distinction. Singing is shouting the praises to the Lord, as is befitting for the mouth of a serious Christian to do. Exulting is declaring the vows of the mind with great affection. Playing the lyre is fulfilling the commandments of the Lord with good deeds. As to the fact that he admonishes this to be done so many times, it is because we must rejoice there in a diverse variety of virtues.

[AD 430] Augustine of Hippo on Psalms 98:2
"The Lord has made known His salvation" [Psalm 98:2]. This very right hand, this very arm, this very salvation, is our Lord Jesus Christ of whom it is said, "And all flesh shall see the salvation of God;" [Luke 3:6] of whom also that Simeon who embraced the Infant in his arms, spoke, "Lord, now let Your servant depart in peace; for my eyes have seen Your salvation." [Luke 2:28-30] "The Lord has made known His salvation." To whom did He make it known? To a part, or to the whole? Not to any part specially. Let no man betray, no man deceive, no man say, "Lo, here is Christ, or there:" [Matthew 24:23] the man who says, Lo, He is here, or there, points to some particular spots. To whom "has the Lord declared His salvation"? Hear what follows: "His righteousness has He openly showed in the sight of the heathen." Our Lord and Saviour Jesus Christ is the right hand of God, the arm of God, the salvation of God, and the righteousness of God.

[AD 430] Augustine of Hippo on Psalms 98:3
"He has remembered His mercy to Jacob, and His truth unto the house of Israel" [Psalm 98:3]. What means this, "He has remembered His mercy and truth"? He has pitied, so that He promised; because He promised and showed His mercy, truth has followed: mercy has gone before promise, promise has been fulfilled in truth....

"And His truth unto the house of Israel." Who is this Israel? That ye may not perchance think of one nation of the Jews, hear what follows: "All the ends of the world have seen the salvation of our God." It is not said, all the earth: but, "all the ends of the world:" as it is said, from one end to the other. Let no man cut this down, let no man scatter it abroad; strong is the unity of Christ. He who gave so great a price, has bought the whole: "All the ends of the world."

[AD 430] Augustine of Hippo on Psalms 98:4
Because they have seen, then, "Make a joyful noise unto the Lord, all you lands" [Psalm 98:4]. You already know what it is to make a joyful noise. Rejoice, and speak. If you cannot express your joy, shout ye; let the shout manifest your joy, if your speech cannot: yet let not joy be mute; let not your heart be silent respecting its God, let it not be mute concerning His gifts. If you speak to yourself, unto yourself are you healed; if His right hand has healed you for Him, speak thou unto Him for whom you have been healed. "Sing, rejoice, and make melody."

[AD 430] Augustine of Hippo on Psalms 98:5-6
"Make melody unto the Lord upon the harp: on the harp and with the voice of a Psalm" [Psalm 98:5]. Praise Him not with the voice only; take up works, that you may not only sing, but work also. He who sings and works, makes melody with psaltery and upon the harp. Now see what sort of instruments are next spoken of, in figure: "With ductile trumpets also, and the sound of the pipe of horn" [Psalm 98:6]. What are ductile trumpets, and pipes of horn? Ductile trumpets are of brass: they are drawn out by hammering; if by hammering, by being beaten, you shall be ductile trumpets, drawn out unto the praise of God, if you improve when in tribulation: tribulation is hammering, improvement is the being drawn out. Job was a ductile trumpet, when suddenly assailed by the heaviest losses, and the death of his sons, become like a ductile trumpet by the beating of so heavy tribulation, he sounded thus: "The Lord gave, and the Lord has taken away; blessed be the name of the Lord." [Job 1:21] How did he sound? How pleasantly does his voice sound? This ductile trumpet is still under the hammer....We have heard how he was hammered; let us hear how he sounds: let us, if it please you, hear the sweet sound of this ductile trumpet: "What! shall we receive good at the hand of God, and shall we not receive evil?" O courageous, O sweet sound! Whom will not that sound awake from sleep? Whom will not confidence in God awake, to march to battle fearlessly against the devil; not to struggle with his own strength, but His who proves him. For He it is who hammers: for the hammer could not do so of itself....See how (I dare so speak, my brethren) even the Apostle was beaten with this very hammer: he says, "there was given to me a thorn in the flesh, the messenger of Satan, to buffet me." [2 Corinthians 12:7-10] Behold he is under the hammer: let us hear how he speaks of it: "For this thing," he says, "I besought the Lord thrice, that it might depart from me. And He said unto me, My grace is sufficient for you: for My strength is made perfect in weakness." I, says His Maker, wish to make this trumpet perfect; I cannot do so unless I hammer it; in weakness is strength made perfect. Hear now the ductile trumpet itself sounding as it should: "When I am weak, then am I strong."...

[AD 430] Augustine of Hippo on Psalms 98:7-8
While you are rejoicing, and delighted with the ductile trumpets, and the voice of the horn, what follows? "Let the sea be stirred up, and the fullness thereof" [Psalm 98:7]. Brethren, when the Apostles, like ductile trumpets and horns, were preaching the truth, the sea was stirred up, its waves arose, tempests increased, persecutions of the Church took place. Whence has the sea been stirred up? When a joyful noise was made, when Psalms of thanksgiving were being sung before God: the ears of God were pleased, the waves of the sea were raised. "Let the sea be stirred up, and the fullness thereof: the round world, and all that dwell therein." Let the sea be stirred up in its persecutions. "Let the floods clap their hands together" [Psalm 98:8]. Let the sea be aroused, and the floods clap their hands together; persecutions arise, and the saints rejoice in God. Whence shall the floods clap their hands? What is to clap their hands? To rejoice in works. To clap hands, is to rejoice; hands, mean works. What floods? Those whom God has made floods, by giving them that Water, the Holy Spirit. "If any man thirst," says He, "let him come unto Me, and drink. He that believes in Me, out of his bosom shall flow rivers of living water." [John 7:37-39] These rivers clapped their hands, these rivers rejoiced in works, and blessed God. "The hills shall be joyful together."

[AD 339] Eusebius of Caesarea on Psalms 98:9
It is prophesied here that the coming of the Lord will be the cause of great benefits to the nations, which have been proved to have actually accrued to them, through the manifestation of our Savior. For of a truth from then and not before the new song of the new covenant has been sung among all people, and his wonders have been known and heard by all people through the written Gospels. And salvation also, by the resurrection of the Lord from the dead, has been revealed to all nations, and the true righteousness, by which it has been clearly proved that God is not the God of the Jews only, but of the Gentiles. “Since there is one God,” in the words of the holy apostle, “who will judge the circumcised from their faith, and the uncircumcised through faith.” And the words “for he, comes to judge the earth,” might refer also to his second coming.”

[AD 430] Augustine of Hippo on Psalms 98:9-10
"Before the Lord, for He has come; for He has come to judge the earth" [Psalm 98:9]. "The hills" signify the great. The Lord comes to judge the earth, and they rejoice. But there are hills, who, when the Lord is coming to judge the earth, shall tremble. There are therefore good and evil hills; the good hills, are spiritual greatness; the bad hills, are the swelling of pride. "Let the hills be joyful together before the Lord, for He has come; for He has come to judge the earth." Wherefore shall He come, and how shall He come? "With righteousness shall He judge the world, and the people with equity" [Psalm 98:10]. Let the hills therefore rejoice; for He shall not judge unrighteously. When some man is coming as a judge, to whom the conscience cannot lie open, even innocent men may tremble, if from him they expect a reward for virtue, or fear the penalty of condemnation; when He shall come who cannot be deceived, let the hills rejoice, let them rejoice fearlessly; they shall be enlightened by Him, not condemned; let them rejoice, because the Lord will come to judge the world with equity; and if the righteous hills rejoice, let the unrighteous tremble. But behold, He has not yet come: what need is there they should tremble? Let them mend their ways, and rejoice. It is in your power in what way you will to await the coming of Christ. For this reason He delays to come, that when He comes He may not condemn you. Lo, He has not yet come: He is in heaven, thou on earth: He delays His coming, do not thou delay wisdom. His coming is hard to the hard of heart, soft to the pious. See therefore even now what you are: if hard of heart, you can soften; if you are soft, even now rejoice that He will come. For you are a Christian. Yea, you say, I believe that you pray, and sayest, "Your kingdom come." [Matthew 6:10] You desire Him to come, whose coming you fear. Reform yourself, that you may not pray against yourself.