佛說目連問戒律中五百輕重事經 2.182

2.182

問：「見人行欲不呵，犯事不？」答：「前人可諫，不諫犯捨墮。若不可諫，向一比丘好發露。」

Question: "If one sees someone engaging in lustful acts and does not admonish him, does one commit an offense or not?" Answer: "If the other person can be admonished, failing to admonish him constitutes a naiḥsargika-pāyattika. If he cannot be admonished, one should properly disclose it to one bhikṣu."