[349] Now at that time, while a certain bhikkhu was thinking a sensual thought (kāmavitakka), semen was emitted. He became anxiously remorseful (kukkucca) … [the passage is abbreviated in the Pali (pe); the fuller formula elsewhere runs: "…thinking, 'Surely I have committed a saṅghādisesa offense.' He reported the matter to the Blessed One. The Blessed One asked: 'Bhikkhu, what were you thinking?' …] … "There is no offense (anāpatti) for a bhikkhu who is thinking a sensual thought."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.