http://buddhasutra.com/files/ambattha_sutta.htm
Then the Lord said to Ambattha,
"Ambattha, I have a fundamental question for you, which you will not like to answer. If you don’t answer, or if you evade the issue, if you keep silent or go away, your head will split into seven pieces. What do you think, Ambattha? Have you heard from old and venerable Brahmins, teachers of teachers, where the Kanhayans came from, or who was their ancestor?"
At this, Ambattha remained silent, and the Lord said,
"Answer me now, Ambattha, this is not the time for silence.
Whoever, Ambattha, does not answer a fundamental question put to him by a Tathágata by the third asking has his head split into seven pieces."
And at that moment Vajrapani the Yaksha, [This god is also called "Indra." He is ready to make good on the mytho mentioned above. The old gods are supporting the new religion. Vajrapani also appears as a Bodhisattva in later Mahayana Sutras.—BIONA Webmaster] holding up a huge iron club, flaming, ablaze and glowing, up in the sky just above Ambattha was thinking, "If this young man does not answer a proper question put to him by the Blessed Lord by the third time of asking, I’ll split his head into seven pieces!"
The Lord saw Vajrapani, and so did Ambattha. And at the sight, Ambattha was terrified and unnerved, his hairs stood on end, and he sought protection, shelter, and safety from the Lord. Crouching down close to the Lord, he said, "What did the Reverend Gotama say? May the Reverend Gotama repeat what he said!"