"But I have walked in mine innocence: deliver me, and have mercy on me" [Psalm 26:11]. Let so great a price of my Lord's Blood avail for my complete deliverance: and in the dangers of this life let not Your mercy leave me.
“Redeem me,” means, make me free through the precious blood of your first advent by which the world was delivered when it was being held subject to sins. “And have mercy on me,” that is to say, in his world, where you pardon those who pray to you faithfully.
[AD 430] Augustine of Hippo on Psalms 26:11