四分律比丘含注戒本 2.201

2.201

彼為僧差教授尼，日未暮當還。除教授，若受經，若誦經，若問，若以餘事，乃至日暮；除尼，若為婦女餘人受經等至暮——一切突吉羅也。

When he is assigned by the Saṃgha to instruct the bhikṣuṇīs, he must return before sunset. Apart from instructing, if he transmits a sutra, recites a sutra, answers questions, or engages in other matters up until sunset; or apart from bhikṣuṇīs, if he transmits a sutra or the like to laywomen or other persons until sunset—in all [such cases, it is a] duṣkṛta.