Looking for a teacher
The canon is clear about what to look for and quiet about where to look. The Buddha told monks to examine even him — by checking what could be seen and heard of his conduct for any sign of corruption — and told the Kālāmas not to accept a teacher on reputation or lineage. So the test is observable conduct, over time, and whether what they teach can be checked in your own experience. Until you find one, the practice is not on hold: the instructions are in the suttas in plain words, and a good friend in the practice was said to be all of the path. Nothing here ranks traditions or names teachers.
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.
“Sir, good friends, companions, and associates are half the spiritual life.” Not so, Ānanda! Not so, Ānanda! Good friends, companions, and associates are the whole of the spiritual life. A mendicant with good friends, companions, and associates can expect to develop and cultivate the noble eightfold path.
Ānanda says half; the Buddha says all of it.
Where this stops: Never used to make someone without such friends feel that their practice is lacking.
SN 45.2:1.4–2.3 · Half the Spiritual Life
“upaḍḍhamidaṁ, bhante, brahmacariyaṁ, yadidaṁ—kalyāṇamittatā kalyāṇasahāyatā kalyāṇasampavaṅkatā”ti. Mā hevaṁ, ānanda, mā hevaṁ, ānanda. Sakalamevidaṁ, ānanda, brahmacariyaṁ, yadidaṁ—kalyāṇamittatā kalyāṇasahāyatā kalyāṇasampavaṅkatā. Kalyāṇamittassetaṁ, ānanda, bhikkhuno pāṭikaṅkhaṁ kalyāṇasahāyassa kalyāṇasampavaṅkassa—ariyaṁ aṭṭhaṅgikaṁ maggaṁ bhāvessati, ariyaṁ aṭṭhaṅgikaṁ maggaṁ bahulīkarissati.
It’s when a mendicant—gone to a wilderness, or to the root of a tree, or to an empty hut—sits down cross-legged, sets their body straight, and brings mindfulness to the present. Just mindful, they breathe in. Mindful, they breathe out. Breathing in heavily they know: ‘I’m breathing in heavily.’ Breathing out heavily they know: ‘I’m breathing out heavily.’
The first instruction in the Satipaṭṭhāna Sutta, in full and without elaboration.
MN 10:4.2–4.4 · Mindfulness Meditation
Idha, bhikkhave, bhikkhu araññagato vā rukkhamūlagato vā suññāgāragato vā nisīdati, pallaṅkaṁ ābhujitvā, ujuṁ kāyaṁ paṇidhāya, parimukhaṁ satiṁ upaṭṭhapetvā. So satova assasati, satova passasati. Dīghaṁ vā assasanto ‘dīghaṁ assasāmī’ti pajānāti, dīghaṁ vā passasanto ‘dīghaṁ passasāmī’ti pajānāti,
Mendicants, these four things can be known in four situations. What four? You can get to know a person’s ethics by living with them. But only after a long time, not casually; only when attentive, not when inattentive; and only by the wise, not the witless. You can get to know a person’s purity by dealing with them. … You can get to know a person’s resilience in times of trouble. … You can get to know a person’s wisdom by discussion. But only after a long time, not casually; only when attentive, not when inattentive; and only by the wise, not the witless.
How a person is actually known — over a long time, with attention, from close up — a standard that applies to a teacher as much as to anyone.
Where this stops: It counsels patience before trusting and before condemning; it is not a reason to stay close to someone already known to be doing harm.
AN 4.192:1.1–1.6 · Facts
Cattārimāni, bhikkhave, ṭhānāni catūhi ṭhānehi veditabbāni. Katamāni cattāri? Saṁvāsena, bhikkhave, sīlaṁ veditabbaṁ, tañca kho dīghena addhunā, na ittaraṁ; manasikarotā, no amanasikarotā; paññavatā, no duppaññena. Saṁvohārena, bhikkhave, soceyyaṁ veditabbaṁ, tañca kho dīghena addhunā, na ittaraṁ; manasikarotā, no amanasikarotā; paññavatā, no duppaññena. Āpadāsu, bhikkhave, thāmo veditabbo, so ca kho dīghena addhunā, na ittaraṁ; manasikarotā, no amanasikarotā; paññavatā, no duppaññena. Sākacchāya, bhikkhave, paññā veditabbā, sā ca kho dīghena addhunā, na ittaraṁ; manasikarotā, no amanasikarotā; paññavatā, no duppaññenāti.