四分戒本疏卷第一．第二．第三 3.53

3.53

獨與尼屏露主戒二十六　此戒過與女人同室宿無異。屏坐為別　別緣有四。一是尼。二無第三人。三在屏露二處。四共坐便犯。已下正明戒本。此戒因迦留陀夷與偷蘭難陀尼軀藐端正。互有欲意在門外坐。居士共嫌。鴛鴦為譬。比丘舉過。佛便制戒。

The precept on sitting alone with a bhikṣuṇī in a secluded or open place, the twenty-sixth. The fault of this precept is no different from spending the night in the same room with a woman; sitting in seclusion is the distinction. There are four specific conditions: first, she is a bhikṣuṇī; second, there is no third person; third, they are in either a secluded or an open place; fourth, sitting together immediately incurs an offense. Below is the proper explanation of the Prātimokṣa text. This precept arose because Udāyin and the bhikṣuṇī Thullanandā were both handsome and well-featured; mutually harboring lustful intentions, they sat outside the gate. Householders shared in disdaining them, using mandarin ducks as a metaphor. The bhikṣus reported the fault, and the Buddha then promulgated the precept.