Psalm 51:1-6 (ESV)
1 Have mercy on me, O God,
according to your steadfast love;
according to your abundant mercy
blot out my transgressions.
2 Wash me thoroughly from my iniquity,
and cleanse me from my sin!
3 For I know my transgressions,
and my sin is ever before me.
4 Against you, you only, have I sinned
and done what is evil in your sight,
so that you may be justified in your words
and blameless in your judgment.
5 Behold, I was brought forth in iniquity,
and in sin did my mother conceive me.
6 Behold, you delight in truth in the inward being,
and you teach me wisdom in the secret heart.
The Psalm has a rich liturgical history. Medieval England observed Ash Wednesday with the recitation of it (along with the 6 other penitential Psalms) to mark the beginning of Lent. Psalm 51 was retained in the Ash Wednesday service of the 1549 Anglican Prayer Book, as were prayers concerning the imposition of ashes from the English variant of the Roman Rite.
Psalm 51 was recited daily for 1300 years in monastic chapels. The devotional quality of the Psalm finds resonance over the centuries in public rites and worship because of the private uses to which it has been put.
Cassiodorus in sixth-century Spain argued that instead of wallowing in their sins, believers should put the message of the Psalms into effect and become good penitents. To make a break with past sins, he argued, one must find words with which the pain of guilty shame can be expressed. That’s hard for us to accomplish because we are all steeped in our sins. In turning to the Psalms– reading them or hearing them read–we can trigger the inner work needed for contrition after achieving the acknowledgement of doing what is wrong. Cassiodorus singled out Psalm 51 in particular as having the profundity to almost miraculously move us to introspection and sorrow over our separation from God.
Other fathers of the early church found in David a perfect model for penitents because his words and actions provide a unified language for the disparate moral sentiments of the entire Christian community. In touching on the power of Psalm 51, St. Augustine admonished his congregation that:
Nathan the prophet has not been sent to you. David has been sent to you. Hear him clamoring, and likewise clamor; hear him moaning, and moan with him; hear him weeping, and add your tears; hear he is corrected, and share in his delight.
Merciful Father, who sent thy messengers the prophets to preach repentance and prepare the way for salvation through thine only Son Jesus Christ our Lord, give us grace to heed holy cautions presented to us against eternal loss, and teach us through thy Spirit to forsake our sins, that we may with great joy greet thee on our ascension unto the matchless life of glory, heaven itself. Amen.