[151] Then the Blessed One said this to the young brahmin Ambaṭṭha: "Ambaṭṭha, this legitimate question (sahadhammika pañha) now comes to you; even if unwilling, you must answer it. If you do not answer, or evade the point with something else, or remain silent, or depart, your head will split into seven pieces right here.
What do you think, Ambaṭṭha? What have you heard from aged, elderly brahmins, teachers of teachers, when they spoke: from what origin do the Kaṇhāyanas descend, and who is the forefather of the Kaṇhāyanas?"
When this was said, the young brahmin Ambaṭṭha remained silent. A second time the Blessed One said this to the young brahmin Ambaṭṭha: "What do you think, Ambaṭṭha? What have you heard from aged, elderly brahmins, teachers of teachers, when they spoke: from what origin do the Kaṇhāyanas descend, and who is the forefather of the Kaṇhāyanas?"
A second time the young brahmin Ambaṭṭha remained silent.
Then the Blessed One said this to the young brahmin Ambaṭṭha: "Answer now, Ambaṭṭha; this is not the time for you to remain silent. Ambaṭṭha, whoever, when asked a legitimate question by the Tathāgata up to the third time, does not answer, his head will split into seven pieces right there."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.