If 52 why not 53?

A dacoit with 52 murders to his credit decided to reform. With a contrite heart he went to a temple of Shiva, confessed his sins and prayed for pardon, promising never again to commit such of offenses. His life thereafter was one of prayers and penances.
Once while walking in a lonely forest in the evening he heard cries for help. On going to the spot where the cries were coming from, he found a band of travelers attacked by a ruffian. If he was to save them there was no alternative to killing the ruffian, and all killing he had forsworn. What was he to do? Thinking quickly, he decided, “If 52, why not 53?” One more murder won't add so much to my sins.“ And straightway he killed the ruffian and rescued the travelers.
But he was perturbed greatly at having broken his promise to the great Lord Shiva. He prayed to be forgiven for his lapse. Suddenly he heard the God's voice, “Take heart, my son, for you have committed no sin but an act of merit. You have , by this act, sufficiently atoned for all your previous sins.”

Author: Swami Sambuddhananda

Source: VTS