When a teacher in your community is found to have done harm
The Buddha's own instructions for scrutinizing a teacher assume that teachers can fail, and the tradition has a rule for what to do when a teaching and its source come apart — check it against the suttas, not against the person. What you learned that holds up under that check is still yours. The grief is real and the suttas would not hurry it. They also say a great deal about speech in a divided community, and nothing about staying loyal to someone who is harming people. If you or others were harmed, the first conversation is with people who can act, not with a passage.
What the suttas say
don’t go by oral transmission, don’t go by lineage, don’t go by testament, don’t go by canonical authority, don’t rely on logic, don’t rely on inference, don’t go by reasoned train of thought, don’t go by the acceptance of a view after deliberation, don’t go by the appearance of competence, and don’t think “The ascetic is our respected teacher.” But when you know for yourselves:
The Kālāma discourse — the canon's charter for testing teachings.
Where this stops: It is not permission to believe whatever one likes; it ends with what the wise praise. Never a reason to stay with a teacher who is doing harm.
AN 3.65:25.3–25.4 · With the Kālāmas of Kesamutta
Mā anussavena, mā paramparāya, mā itikirāya, mā piṭakasampadānena, mā takkahetu, mā nayahetu, mā ākāraparivitakkena, mā diṭṭhinijjhānakkhantiyā, mā bhabbarūpatāya, mā samaṇo no garūti. Yadā tumhe kālāmā attanāva jāneyyātha:
Mendicants, a mendicant who is an inquirer, unable to encompass another’s mind, should scrutinize the Realized One for two things—things that can be seen and heard: ‘Can anything corrupt be seen or heard in the Realized One or not?’ Scrutinizing him they find that nothing corrupt can be seen or heard in the Realized One.
The Buddha's own instructions for scrutinizing a teacher, including himself.
Where this stops: Never a reason to stay with a teacher who is doing harm.
MN 47:4.1–4.4 · The Inquirer
Vīmaṁsakena, bhikkhave, bhikkhunā parassa cetopariyāyaṁ ajānantena dvīsu dhammesu tathāgato samannesitabbo cakkhusotaviññeyyesu dhammesu: ‘ye saṅkiliṭṭhā cakkhusotaviññeyyā dhammā, saṁvijjanti vā te tathāgatassa no vā’ti? Tamenaṁ samannesamāno evaṁ jānāti: ‘ye saṅkiliṭṭhā cakkhusotaviññeyyā dhammā, na te tathāgatassa saṁvijjantī’ti.
You should neither approve nor reject that mendicant’s statement. Instead, having carefully memorized those words and phrases, you should make sure they fit in the discourse and are exhibited in the training.
The four great references — a teaching claimed to be the Buddha's is checked against the suttas and the training, not against the authority of whoever says it.
Where this stops: A method for testing claims about what the Buddha taught, not a licence to dismiss a living teacher's practical instruction because it is not quoted in a sutta.
AN 4.180:2.5–2.6 · The Four Great References
Tassa, bhikkhave, bhikkhuno bhāsitaṁ neva abhinanditabbaṁ nappaṭikkositabbaṁ. Anabhinanditvā appaṭikkositvā tāni padabyañjanāni sādhukaṁ uggahetvā sutte otāretabbāni, vinaye sandassetabbāni.
Now, Ānanda, some of you might think: ‘The teacher’s dispensation has passed. Now we have no Teacher.’ But you should not see it like this. The teaching and training that I have taught and pointed out for you shall be your Teacher after my passing.
The Buddha's own answer to the fear of losing a teacher — the teaching and the training are the teacher that remains.
Where this stops: Said by the Buddha of himself, at the end of his life, to his monks; it is not a judgement that living teachers are unnecessary. Never a reason to look past a teacher's harm or stay quiet about it.
DN 16:6.1.2–6.1.5 · The Great Discourse on the Buddha’s Extinguishment
siyā kho panānanda, tumhākaṁ evamassa: ‘atītasatthukaṁ pāvacanaṁ, natthi no satthā’ti. Na kho panetaṁ, ānanda, evaṁ daṭṭhabbaṁ. Yo vo, ānanda, mayā dhammo ca vinayo ca desito paññatto, so vo mamaccayena satthā.
“In the same way, prince, the Realized One does not utter speech that he knows to be untrue, false, and pointless, and which is disliked by others. The Realized One does not utter speech that he knows to be true and correct, but which is harmful and disliked by others. The Realized One knows the right time to speak so as to explain what he knows to be true, correct, and beneficial, but which is disliked by others. The Realized One does not utter speech that he knows to be untrue, false, and pointless, but which is liked by others. The Realized One does not utter speech that he knows to be true and correct, but which is harmful, even if it is liked by others. The Realized One knows the right time to speak so as to explain what he knows to be true, correct, and beneficial, and which is liked by others. Why is that? Because the Realized One has sympathy for sentient beings.”
Prince Abhaya — the test for whether and when to say a hard thing.
Where this stops: For deciding whether and when to say one particular hard thing; it does not judge a relationship as a whole, and it is not a reason to say nothing. Nor does it mean anyone owes another person news about their own body, health or pregnancy, or should speak when speaking would put them at risk.
MN 58:8.1–8.8 · With Prince Abhaya
“Evameva kho, rājakumāra, yaṁ tathāgato vācaṁ jānāti abhūtaṁ atacchaṁ anatthasaṁhitaṁ sā ca paresaṁ appiyā amanāpā, na taṁ tathāgato vācaṁ bhāsati. Yampi tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ anatthasaṁhitaṁ sā ca paresaṁ appiyā amanāpā, tampi tathāgato vācaṁ na bhāsati. Yañca kho tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ atthasaṁhitaṁ sā ca paresaṁ appiyā amanāpā, tatra kālaññū tathāgato hoti tassā vācāya veyyākaraṇāya. Yaṁ tathāgato vācaṁ jānāti abhūtaṁ atacchaṁ anatthasaṁhitaṁ sā ca paresaṁ piyā manāpā, na taṁ tathāgato vācaṁ bhāsati. Yampi tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ anatthasaṁhitaṁ sā ca paresaṁ piyā manāpā tampi tathāgato vācaṁ na bhāsati. Yañca tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ atthasaṁhitaṁ sā ca paresaṁ piyā manāpā, tatra kālaññū tathāgato hoti tassā vācāya veyyākaraṇāya. Taṁ kissa hetu? Atthi, rājakumāra, tathāgatassa sattesu anukampā”ti.