The Prayer of Jesus is said like this: Lord Jesus Christ, son of God, have mercy on me, a sinner. Originally it was said without the addition of the word sinner: this word was added to the other words of the prayer later. This word, remarks Saint Nil Sorsky, which implies a consciousness and confession of the fall, is fitting for us and pleasing to God who has commanded us to offer prayers in acknowledgement and confession of our sinfulness.
–Saint Ignatius Brianchaninov (1807-1867)