四分比丘戒本疏 2.37

2.37

Fifth: the precept against sleeping in the same room with an unordained person for more than three nights. According to the Vinaya, on the third night, failing to avoid the dawn incurs one prāyaścittika. Nanshan says it incurs a duṣkṛta, but this contradicts the precept text stating that three nights incurs a prāyaścittika. Coming to the fourth night, with each time one's side touches the ground, each incurs a prāyaścittika offence. If on the third night one avoids the dawn, but on the fourth night does not separate by an entire night, if one does not separate, one likewise offends with each turning onto one's side; the characteristics of the room are as before. There is no leisure to discuss at length the agreements and differences with other vinayas.