"Have mercy on me, O God, according to your unfailing love; according to your great compassion blot out my transgressions." (Psalm 51:1 NIVUK)  A woman once approached Napoleon seeking a pardon for her son, who had stolen from the Royal Palace on more than one occasion. The Emperor replied that justice demanded the young man be put to death. "But I don’t ask for justice," the mother explained, "I plead for mercy." "Your son does not deserve mercy," Napoleon said. "Sir," the woman cried, "it would not be mercy if he deserved it, and mercy is all I ask for." "Well, then," the Emperor decided, "I will have mercy."  Similarly, David (the writer of Psalm 51), having committed the sin of adultery with Bathsheba and then gone on to compound that wrong with other ill-judged actions, pleaded in prayer with the LORD to show mercy. Notice, that he did not ask for God to weigh-up his good deeds against the bad. Nor, did he make bold promises to be a better man in the future. His appeal for mercy was based simply upon the character of God, Who is loving, compassionate and merciful at heart.