20 “O Lord, my lips You shall open, and my mouth shall tell of Your praise”. “Your praise,” because I have been created: “Your praise,” because sinning I have not been forsaken: “Your praise,” because I have been admonished to confess: “Your praise,” because in order that I might be secured I have been cleansed.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)