Veḷuka Jātaka (No.43)
The Bodhisatta was once at the head of five hundred hermits, one of whom had a pet viper which was called Veḷuka, because it was kept in a bamboo. The Bodhisatta warned the ascetic against the snake, but his warning was not heeded. The hermit thus came to be called Veḷukapitā. One day the hermits went into the forest and were away for a few days, and when Veḷukapitā touched the viper on his return, the animal, hungry and angry, bit him, and he fell down dead. The story was told in reference to a headstrong monk who is identified with Veḷukapitā. J.i.245 f.