[352] Now at that time, as a certain bhikkhu was scratching his scrotum, semen was emitted. He became anxious with remorse … [He reported the matter to the Blessed One. "With what mind did you act, bhikkhu?" "I had no intention of causing emission, Blessed One."] "There is no offense (āpatti), bhikkhu, for one without intention of causing emission."
Now at that time, as a certain bhikkhu, intending to cause emission, was scratching his scrotum, semen was emitted … ["With what mind did you act, bhikkhu?" "I intended to cause emission, Blessed One." "Bhikkhu, you have committed an offense entailing a formal meeting of the Saṅgha (saṅghādisesa)."] … [as a certain bhikkhu, intending to cause emission, was scratching his scrotum,] semen was not emitted. He became anxious with remorse … ["With what mind did you act, bhikkhu?" "I intended to cause emission, Blessed One."] "There is no offense entailing a formal meeting of the Saṅgha, bhikkhu; there is a grave offense (thullaccaya)."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.