27 “Though they curse, yet bless Thou”. Vain therefore and false is the cursing of the sons of men, that have pleasure in vanity, and seek a lie; but when God blesses, He does what He says. “Let them be confounded that rise up against me.” For their imagining that they have some power against Me, is the reason that they rise up against Me; but when I shall have been exalted above the heavens, and My glory shall have commenced spreading over the whole earth, they shall be confounded. “But Your servant shall rejoice:” either on the right hand of the Father, or in His members when they rejoice, both in hope among temptations, and after temptations for evermore.
28. “Let my slanderers be clothed with shame”: that is, let it shame them to have slandered me. But this may also be understood as a blessing, in that they are amended. “And let them cover themselves with their own confusion, as with a double cloak;” for diplois is a double cloak; that is, let them be confounded both within and without: both before God and before men.
29. “As for me, I will confess greatly unto the Lord with my mouth”....Is He said to “praise among the multitude” because He is with His Church here even unto the end of the world; so that we may understand by “among the multitude,” that He is honoured by this very multitude? For he is said to be in the midst, unto whom the chief honour is paid. But if the heart is, as it were, that which is mid-most of a man, no better construction can be put on this passage than this, I will praise Him in the hearts of many. For Christ dwells through faith in our hearts; and therefore he says, “with my mouth,” that is, with the mouth of my body, which is the Church.
30. “For He stood at the right hand of the poor”. It was said of Judas, “Let Satan stand at his right hand;” since he chose to increase his riches by selling Christ; but here the Lord stood at the right hand of the poor, that the Lord Himself might be the poor man's riches. “He stood at the right hand of the poor,” not to multiply the years of a life that one day must end, nor to increase his stores, nor to render him strong in the strength of the body, or secure for a time; “but,” he says, “to save my soul from the persecutors.” Now the soul is rendered safe from the persecutors, if we do not consent to them unto evil; but there is no such consent to them when the Lord stands at the right hand of the poor, that he may not give way through his very poverty, that is, weakness. This aid was given to the Body of Christ in the case of all the holy Martyrs.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)