Augustine of Hippo

Baptized people, though, who are deserters and violators of such a great sacrament, if they repent from the bottom of their hearts, if they repent where God can see, as he saw David's heart, when on being rebuked by the prophet, and very sternly rebuked, he cried out after hearing God's fearsome threats and said, "I have sinned," and shortly afterward heard, "God has taken away your sin." Such is the effectiveness of three syllables. "I have sinned" is just three syllables; and yet in these three syllables the flames of the heart's sacrifice rose up to heaven. So those who have done genuine penance, and have been absolved from the constraints by which they were bound and cut off from the body of Christ, and have lived good lives after their penance, such as they ought to have lived before penance, and in due course have passed away after being reconciled, why, they too go to God, go to their rest, will not be deprived of the kingdom, will be set apart from the people of the devil.