A jackal, seeing a lion, expressed his wish to be his servant. The lion agreed and provided him with food. On growing strong, the jackal offered to kill an elephant and, in spite of the lion's warnings, was trampled to death. The lion was the Bodhisatta and the jackal Devadatta.
The story was related in reference to Devadatta's attempt to imitate the Buddha. J.iii.112ff.