四分律比丘含注戒本 2.207

2.207

若說不了了，吉羅。比丘尼等吉羅。不犯者：其事實爾，為飲食供養故教授，為飲食故教誦經、受經，若問；若戲，若錯說者——一切不犯。

If spoken unclearly, it is a duṣkṛta. For bhikṣuṇīs and others, it is a duṣkṛta. Non-offences: if it is indeed a fact that he instructs for the sake of food and offerings, or teaches them to recite sutras, transmits sutras, or answers questions for the sake of food and drink; if spoken in jest, or said by mistake—in all [such cases] there is no offence.