22 And what shall we sing there, save His praises? What else shall we say there, save, “You are my God, and I will confess unto You; You are my God, and I will praise You. I wilt confess unto You, for You have heard me, and art become my Salvation.” We will not say these things in loud words; but the love that abides in Him of itself cries out in these words, and these words are love itself. Thus as he began with praise, so he ends: “Confess unto the Lord, for He is gracious, and His mercy endures for ever”. With this the Psalm commences, with this it ends; since, as from the commencement which we have left behind, so in the end, whither we are returning, there is not anything that can more profitably please us, than the praise of God, and Allelujah evermore.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)