5 “Have pity on me, O God, have pity on me, for in You has trusted my Soul”. Christ in the Passion says, “Have pity on Me, O God.” To God, God says, “Have pity on Me!” He that with the Father has pity on you, in you cries, “Have pity on Me.” For that part of Him which is crying, “Have pity on Me,” is yours: from you this He received, for the sake of you, that you should be delivered, with Flesh He was clothed. The flesh itself cries: “Have pity on Me, O God, have pity on me:” Man himself, soul and flesh.
For whole Man did the Word take upon Him, and whole Man the Word became. Let it not therefore be thought that there Soul was not, because the Evangelist thus says: “The Word was made flesh, and dwelled in us.” For man is called flesh, as in another place says the Scripture, “And all flesh shall see the salvation of God.” Shall anywise flesh alone see, and shall Soul not be there?...You hear the Master praying, learn thou to pray. For to this end He prayed, in order that He might teach how to pray: because to this end He suffered, in order that He might teach how to suffer; to this end He rose again, in order that He might teach how to hope for rising again.
“And in the shadow of Your wings I will hope, until iniquity pass over.” This now evidently whole Christ does say: here is also our voice. For not yet has passed over, still rife is iniquity. And in the end our Lord Himself said there should be an abounding of iniquity: “And since iniquity shall abound, the love of many shall wax cold; but he that shall have persevered unto the end, the same shall be saved.” But who shall persevere even unto the end, even until iniquity pass over?
He that shall have been in the Body of Christ, he that shall have been in the members of Christ, and from the Head shall have learned the patience of persevering. Thou passest away, and behold passed are your temptations; and you go into another life whither have gone holy men, if holy you have been. Into another life have gone Martyrs; if Martyr you shall have been, you also go into another life. Because “you” have passed away hence, has by any means iniquity therefore passed away? There are born other unrighteous men, as there die some unrighteous men. In like manner therefore as some unrighteous men die and others are born: so some just men go, and others are born. Even unto the end of the world neither iniquity will be wanting to oppress, nor righteousness to suffer....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)