Buddha Shakyamuni once had a disciple, who had been very strong and evil, and had killed 999 persons(maybe 99, I donot remember the exact number) before he came to Buddha Sakyamuni, the aim he came to Buddha Sakyamuni was to kill the great Buddha, he had a ring on his neck made of fingers of the victims. This evil murderer tried to stab Buddha using his knife, but he failed no matter how he tried.
After that this person knew Buddha Shakyamuni was not an ordinary person, so he became the disciple of Buddha, not learn how to fight, but how to cultivate. After quite some time, the relatives of the victims knew the murder had become a kind person, and not to kill others anymore, they came to revenge, they threw stones at the cultivator, he didnot fight back, he died.