Paṭhamaānandasutta
Atha kho āyasmā ānando yena bhagavā tenupasaṅkami; upasaṅkamitvā bhagavantaṁ abhivādetvā ekamantaṁ nisīdi. Ekamantaṁ nisinno kho āyasmā ānando bhagavantaṁ etadavoca: “‘saṅghabhedo saṅghabhedo’ti, bhante, vuccati. Kittāvatā nu kho, bhante, saṅgho bhinno hotī”ti? “Idhānanda, bhikkhū adhammaṁ dhammoti dīpenti, dhammaṁ adhammoti dīpenti, avinayaṁ vinayoti dīpenti …pe… paññattaṁ tathāgatena apaññattaṁ tathāgatenāti dīpenti. Te imehi dasahi vatthūhi avakassanti apakassanti āveni kammāni karonti āveni pātimokkhaṁ uddisanti. Ettāvatā kho, ānanda, saṅgho bhinno hotī”ti.
With Ānanda (1st)
Then Venerable Ānanda went up to the Buddha, bowed, sat down to one side, and said to him: “Sir, they speak of ‘schism in the Saṅgha’. How is schism in the Saṅgha defined?” “Ānanda, it’s when a mendicant explains what is not the teaching as the teaching … and what was prescribed by the Realized One as not prescribed by the Realized One. On these ten grounds they split off and go their own way. They perform legal acts autonomously and recite the monastic code autonomously. That is how schism in the Saṅgha is defined.”