Christian tradition has distinguished seven penitential psalms in the Psalter (Pss. 6, 32, 38, 51, 102; 130; 143) and Psalm 51 is the best known among them. The superscription (verses 1-2) links this psalm to David’s confession in 2 Sam 12:13 after his adultery with Bathsheba, the wife of Uriah, and arranging for Uriah to be killed. But, the psalm reflects the time of Babylonian exile when Jerusalem was destroyed and there was no place to offer sacrifices (see Ps 51:20-21).
Prophet Ezekiel who was among the first group of those sent to Babylon had difficulties in leading his compatriots to repentance. They were quoting a famous proverb, “the fathers have eaten sour grapes, and the children's teeth are set on edge” (Ezek 18:2), which blamed their tragedy on their leaders. In their view, the exile was not the consequence of their sins but an outcome of wrong politics.
The psalm expresses an enormous sense of guilt. In the Book of Ezekiel, God says: “The guilt of the house of Israel and Judah is exceedingly great. The land is full of blood, and the city full of injustice” (Ezek 9:9). The psalmist acknowledges it. He agrees with the pessimistic assessment of the Book of Genesis that “the intention of man's heart is evil from his youth” (Gen 8:21; see Ps 51:7). But, the problem was what to do. There was no place to offer sacrifices for sin offerings. The temple was destroyed and the priesthood did not function.
The psalmist comes up with a novel idea that sincere prayer for forgiveness replaces sacrifices. “My sacrifice, O God, is a contrite spirit”. When the temple was still standing, the Lord was not pleased with the sacrifices because the people made a mockery of God’s commandments. “The land [was] full of blood, and the city full of injustice” (Ezek 9:9). And if not sacrifice then what? The psalmist discovered the way of repentance. The Creator of the Universe, who “does not dwell in houses made by hands” (Acts 7:48), looks with favour on “those who are humble and contrite in spirit, and who tremble at [His] word” (Is 66:2).
One thing, however, we need to keep in mind. Although the psalmist made a sincere confession of sin, we do not hear God’s response to that confession. Prophet Nathan assured David that God forgave his sin (2 Sam 12:13) and in the Book of Isaiah, the Lord declares the iniquity of Jerusalem is pardoned (Is 40:2). And so, we presume that the prayer of the psalmist was also heard. But, the prayer of the psalmist looks forward to the New Testament to hear the words of Jesus, “Your sins are forgiven” (Mark 2:5), and to the ministry of the Church that was given the power to forgive sins (see John 20:23).