Angulimala

Angulimala was a killer who was about to slay his mother to complete his garland of 1,000 fingers (each one taken from a different victim), until the Buddha stepped in to prevent this act of matricide, which would have condemned Angulimala to millennia in hell. Enraged, the mass murderer turned his fury on the Buddha.

Even with his formidable speed, however, Angulimala could not overtake his new nemesis. He ran at him like the madman he was, but still could not catch the Buddha, who simply walked on, calm and serene. 

Exhausted and furious at his failure, Angulimala screamed at the Buddha to stop. In a quiet voice, the Buddha told his would-be attacker that he had already stopped—he had stopped killing and harming living beings, and now it was time for him, Angulimala, to do likewise.

Angulimala was so struck by these words that there and then he threw away his weapons and became a disciple of the Buddha.

This dramatic tale is familiar to almost every Burmese Buddhist as an illustration of the power of metta, the first of the four brahma vihara (byama so in Burmese), the “heavenly abodes” or divine states of mind. It is also the most powerful, since it supports the other three—compassion, sympathetic joy and equanimity.(quote from http://www.irrawaddy.org/article.php?art_id=10619)