9 “Let Your priests be clothed with righteousness, and let Your saints sing with joyfulness”. When Thou risest from the dead, and go unto Your Father, let that royal Priesthood be clothed with faith, since “the righteous lives by faith;” and, receiving the pledge of the Holy Spirit, let the members rejoice in the hope of resurrection, which went before in the Head: for to them the Apostle says, “Rejoicing in hope.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)