29 Again hear this because of that same “again” and “again.” “My lips shall exult when I shall psalm to You”. Because lips are wont to be spoken of both belonging to the inner and to the outward man, it is uncertain in what sense lips have been used: there follows therefore, “And my soul which You have redeemed.” Therefore regarding the inward lips having been saved in hope, brought back from the bottomless places of the earth in faith and love, still however waiting for the redemption of our body, we say what?
Already he has said, “And my soul which You have redeemed.” But lest you should think the soul alone redeemed, wherein now you have heard one “again,” “but still,” he says; why still? “but still my tongue also:” therefore now the tongue of the body: “all day long shall meditate of Your righteousness”: that is, in eternity without end. But when shall this be? Hereafter at the end of the world, at the resurrection of the body and the changing into the Angelic state. Whence is it proved that this is spoken of the end, “but still my tongue also all day long shall meditate of Your righteousness”?
“When they shall have been confounded and shall have blushed, that seek evil things for me.” When shall they be confounded, when shall they blush, save at the end of the world? For in two ways they shall be confounded, either when they shall believe in Christ, or when Christ shall have come. For so long as the Church is here, so long as grain groans amid chaff, so long as wheat groans amid tares, so long as vessels of mercy groan amid vessels of wrath made for dishonour, so long as lily groans amid thorns, there will not be wanting enemies to say, “When shall he die, and his name perish?” “Behold there shall come the time when Christians shall be ended and shall be no more: as they began at a set time, so even unto a particular time they shall be.”
But while they are saying these things and without end are dying, and while the Church is continuing preaching the Arm of the Lord to every generation that is to come; there shall come Himself also at last in His glory, there shall rise again all the dead, each with his cause: there shall be severed good men to the right hand, but evil men to the left, and they shall be confounded that did insult, they shall blush that did mock: and so my tongue after resurrection shall meditate of Your righteousness, all day long of Your praise, “when they shall have been confounded and shall have blushed, that seek evil things for me.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)