16 “Therefore to the Lord I have cried out”. The Body of Christ and the oneness of Christ in anguish, in weariness, in uneasiness, in the tribulation of its exercise, that One Man, Oneness in One Body set, when He was wearying His soul in crying out from the ends of the earth; says, “From the ends of the earth to You I have cried out, when My heart was being vexed.” Himself one, but a oneness that One! And Himself one, not in one place one, but from the ends of the earth is crying as one. How from the ends of the earth should there cry one, except there were one? “I to the Lord have cried out.” Rightly do thou cry out to the Lord, cry not to Donatus: lest for you he be instead of the Lord a lord, that under the Lord would not be a fellow-servant.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)