7 And because this confession leads not to punishment, he continues and says, “Let the nations rejoice and exult”. If robbers after confession made do wail before man, let the faithful after confessing before God rejoice. If a man be judge, the torturer and his fear exact from a robber a confession: yea sometimes fear wrings out confession, pain extorts it: and he that wails in tortures, but fears to be killed if he confess, supports tortures as far as he is able: and if he shall have been overcome by pain, he gives his voice for death.
Nowise therefore is he joyful; nowise exulting: before he confesses the claw tears him; when he has confessed, the executioner leads him along a condemned felon: wretched in every case. But “let the nations rejoice and exult.” Whence? Through that same confession. Why? Because good He is to whom they confess: He exacts confession, to the end that He may deliver the humble; He condemns one not confessing, to the end that He may punish the proud. Therefore be thou sorrowful before you confess, after having confessed exult, now you will be made whole.
Your conscience had gathered up evil humours, with boil it had swollen, it was torturing you, it suffered you not to rest: the Physician applies the fomentations of words, and sometimes He lances it, He applies the surgeon's knife by the chastisement of tribulation: do thou acknowledge the Physician's hand, confess thou, let every evil humour go forth and flow away in confession: now exult, now rejoice, that which remains will be easy to be made whole....“Let the nations rejoice and exult, for You judge the peoples in equity.”
And that unrighteous men may not fear, he has added, “and the nations on the earth You direct.” Depraved were the nations and crooked were the nations, perverse were the nations; for the ill desert of their depravity, and crookedness and perverseness, the Judge's coming they feared: there comes the hand of the same, it is stretched out mercifully to the peoples, they are guided in order that they may walk the straight way; why should they fear the Judge to come, that have first acknowledged Him for a Corrector?
To His hand let them give up themselves, Himself guides the nations on the earth. But guided nations are walking in the Truth, are exulting in Him, are doing good works; and if perchance there comes in any water (for on sea they are sailing) through the very small holes, through the crevices into the hold, pumping it out by good works, lest by more and more coming it accumulate, and sink the ship, pumping it out daily, fasting, praying, doing almsdeeds, saying with pure heart, “Forgive us our debts, as also we forgive our debtors” — saying such words walk thou secure, and exult in the way, sing in the way.
Do not fear the Judge: before you were a believer, you found a Saviour. You ungodly He sought out that He might redeem, you redeemed will He forsake so as to destroy? “And the nations on earth You direct.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)