四分律刪補隨機羯磨 1.419

1.419

"You must under no circumstances commit sexual misconduct or engage in impure conduct. If a bhikṣu commits impure conduct, practicing carnal desire, down to doing so with an animal, he is not a śramaṇa, not a son of the Śākya. At that time, the World-Honoured One spoke a parable for them: 'Just as when a person has his head severed, he can never again be revived, so too is a bhikṣu: having committed a pārājika dharma, he can never again achieve the conduct of a bhikṣu.' In this matter, you must not do so as long as your life lasts; are you able to uphold this?"