It has been noticed that the Aṭṭhasālinī recorded an argument about the canonicity of the Kathāvatthu composed by Moggaliputta-Tissa. The vitaṇḍavādin there rejected it as being sāvakabhāsita (what was spoken by a diciple) and proposed either the Mahādhammahadaya or the Mahādhātukathā instead, while the Aṭṭhasālinī managed to interpret it to be buddhabhāsita (what was spoken by the Buddha). On the one hand, from this discussion one may think that the elders of the Theravāda (Mahāvihāra) fraternity commonly
believed that the three piṭakas called buddhavacana (literally, “Word of the Buddha”) are supposed to consist of only the Buddha’s words. On the other hand, there is a scholar who has a query about equating the three piṭakas with the word of the Buddha, assuming that “a few passages” which remain in the Mahādhammahadaya and the Mahādhātukathā are the Buddha’s original teachings outside of the canon ([清水 2016a]).
The Pāli cmmentaries certainly attempt to interpret some suttas discoursed by the disciples of the Buddha to be buddhabhāsita or jinabhāsita on account of the Buddha’s approval. However, since it is not applicable in most cases, such interpretation cannot be generalized. Furthermore, the Vinayapiṭaka classifies the dhamma into four categories: buddhabhāsita, sāvaka-bh°, isi-bh° (saints) and deva-bh° (deities), and its commentary applies the canonical texts to each category. The Theragāthā and the Therīgāthā are, according to the Pāli comentator, sāvakabhāsitas collected at the council(s). The Pāli commentaries reveal that the executors of the councils (saṅgītikāras) occasionally add their own words and passages to the canon. Thus it is evident from the Theravādin’s point of view that the Pāli canon does not consist exclusively of the Buddha’s
It is also important that the Pāli commentaries recognized that the Buddha’s words exist outside of the canon. The fate after death of the kind Ajātasatthu is exposed by the Buddha in the commentary on the Sāmaññaphalasutta, and this is said to be “certainly told by the Exalted One” (bhagavatā vuttam eva).
When the suttas relate the Buddha pleasing people with a dhammakathā, the commentaries, calling it Pāḷimuttakakathā (the sermon freed from the canon), sometimes reveal the content of the sermon. There is even a case when a non-canonical story is called buddhabhāsita by the commentator. In the Kathāvatthu, we can find unknown suttas accepted as having been “told by the Exalted One” both by the opponents and the Theravādins.
As shown in the expression: “in buddhavacana consisting of three piṭakas listed at three councils” (tisso saṅgītiyo ārūḷhe tepiṭake buddhavacane), buddhavacana is a category term for the three piṭakas collected, approved and authorized at three councils, while buddhabhāsita exist inside and outside of the canon.