律戒本疏 1.19

1.19

二不空法　因迦留陀夷與女人屏處坐。有鹿子母優婆夷得初道。可信人以所見白佛。比丘所犯定是五篇所攝。而彼不知何事何罪何萬所攝罪。雖定見而者不定故。以不定為名。若優婆夷據其罪。自以可信故受其所見。以不審故不受所據。又應問是可信人。汝有證不。答言有證。復應問證。證同則受。異則不受。受可信人語已應取定比丘。定比丘首實便隨事治之。若其不首與實覔羯磨。羯磨不受便驅出覔罪。中間不得作和上及種種師。與人受戒比丘比丘尼。依止師足數人。如是種種不得。猶如得戒沙彌。凡三歸五戒優婆夷亦名可信之人也。

The two undetermined rules (aniyata-dharma): Originating from Kālodayin sitting in a secluded place with a woman. The upāsikā Mṛgāramātṛ had attained the first fruit of the path; being a trustworthy person, she reported what she had seen to the Buddha. The offense committed by the monk definitely fell within the five classes, but she did not know which matter, which offense, or which of the myriad offenses it was subsumed under. Although what she saw was definite, the offense was undetermined; hence it is named 'undetermined'. If the upāsikā relies on the offense, one accepts what she saw because she is personally trustworthy, but because it has not been thoroughly examined, one does not accept the offense she alleges. Furthermore, one should ask this trustworthy person: 'Do you have witnesses?' If she replies: 'I have witnesses,' one should further question the witnesses. If the witness agrees, it is accepted; if discordant, it is not accepted. Having accepted the words of the trustworthy person, one should interrogate the monk to determine the facts. If the monk confesses the truth, he is dealt with according to the facts. If he does not confess, a karmavācanā to search for the facts is performed. If he does not accept the karmavācanā, he is expelled to investigate the offense. In the interim, he may not serve as an upādhyāya or various kinds of teachers, administer the precepts to male or female monastics, serve as an āśraya teacher, or count among the requisite quorum; in such various ways he is disallowed, just like a newly ordained novice. In general, an upāsikā who has taken the three refuges and the five precepts is also termed a 'trustworthy person'.