Atthinukhopariyāya Sutta 'Is there a Method?' (SN. 35.153).
Atthi bhikkhave, pariyāyo yaṃ pariyāyaṃ āgamma bhikkhu aññatreva saddhāya aññatra ruciyā aññatra anussavā aññatra ākāraparivitakkā aññatra diṭṭhinijjhānakkhantiyā aññaṃ vyākareyya: “khīṇā jāti, vusitaṃ brahmacariyaṃ, kataṃ karaṇīyaṃ nāparaṃ itthattāyāti pajānāmī”
“There is, bhikkhus, a method and procedure through which a bhikkhu: not by faith, not by preferences, not by what was said, not by circular reasoning, not by acceptance of a theory one favors; but one by which can be proclaimed with direct knowledge ‘exhausted is birth, fulfilled is the highest aspiration, done is what had to be done, there is nothing more for this existence.’…
Idha bhikkhave, bhikkhu cakkhunā rūpaṃ disvā santaṃ vā ajjhattaṃ rāgadosamohaṃ atthi me ajjhattaṃ rāgadosamohoti pajānāti, asantaṃ vā ajjhattaṃ rāgadosamohaṃ natthi me ajjhattaṃ rāgadosamohoti pajānāti
“Here, bhikkhus, having seen an object with the eye – if there is desire, corrupt intentions, and delusion within oneself, a bhikkhu directly knows ‘desire, corrupt intentions, and delusion are within me’; or if there is not desire, corrupt intentions and delusion within oneself, he directly knows ‘desire, corrupt intentions and delusion do not exist within me.’ Bhikkhus, so it is that with this seeing an object with the eye …
SN. 36.3 – Pahānasuttaṃ
Discourse on Abandoning
Tisso imā bhikkhave vedanā. Katamā tisso, sukhā vedanā dukkhā vedanā adukkhamasukhā vedanā. Sukhāya bhikkhave vedanāya rāgānusayo pahātabbo, dukkhāya vedanāya paṭighānusayo pahātabbo, adukkhamasukhāya, vedanāya avijjānusayo pahātabbo.
“Bhikkhus, there is this triad of sensations of feeling, what triad? Pleasant sensations of feeling, unpleasant sensations of feeling, and neither pleasant nor unpleasant sensations of feeling. Bhikkhus, the underlying tendency of desire is to be abandoned with pleasant sensations of feeling; the underlying tendency of anger is to be abandoned with unpleasant sensations of feeling; the underlying tendency of ignorance is to be abandoned with neither pleasant nor unpleasant sensations of feeling.
Yato kho bhikkhave bhikkhuno sukhāya vedanāya rāgānusayo pahīno hoti dukkhāya vedanāya paṭighānusayo pahīno hoti, adukkhamasukhāya vedanāya avijjānusayo pahīno hoti, ayaṃ vuccati bhikkhave bhikkhu. Pahīnarāgānusayo acchecchi taṇhaṃ, vāvattayī, saññojanaṃ sammāmānābhisamayā antamakāsi dukkhassāti.
“Bhikkhus, whenever a bhikkhu has abandoned the underlying tendency of desire with pleasant sensations of feeling; has abandoned the underlying tendency of anger with unpleasant sensations of feeling; has abandoned the underlying tendency of ignorance with neither pleasant nor unpleasant sensations of feeling – Bhikkhus, that bhikkhu is said to have abandoned latent desire, cut-off craving, turned away from the fetters, has completely penetrated presumption – and has made an end of dukkha.”
Sukhaṃ vediyamānassa vedanaṃ appajānato
So rāgānusayo hoti anissaraṇadassino.
“If one experiences pleasure,
Without direct-knowledge of the sensation;
One has latent desire,
And will not find escape.
Dukkhaṃ vediyamānassa vedanaṃ appajānato
Paṭighānusayo hoti anissaraṇadassino.
“If one experiences displeasure,
Without direct-knowledge of the sensation;
One has anger,
And will not find escape.
Adukkhamasukhaṃ santaṃ bhuripaññena desitaṃ
Taṃ cāpi abhinandanto neva dukkhā pamuccati.
And the neither pleasant nor unpleasant,
Peaceful though the wise have taught;
If through pleasure he is pulled along,
Will not be freed from dukkha.
Yato vā. Bhikkhu ātāpī sampajaññaṃ na riñcati
Tato so vedanā sabbā parijānāti paṇḍito.
“But whenever a bhikkhu does not abandon,
Intense endeavor and clear-knowing;
There the wise one clearly knows,
All sensations of feeling.
So vedanā pariññāya, diṭṭhe dhamme anāsavo.
kāyassa bhedā dhammaṭṭho, saṅkhyaṃ nopeti vedagū”ti.
Sensations of feeling now clearly known,
In this state he is free of taints;
And with the break up of the body,
The wise one gone beyond calculation.