大般涅槃經義記 6.424

6.424

下就設難，難有三階：一就地前凡夫設難，若未聞時已有聞者，「一切眾生未有菩提即應有之，未得涅槃亦應得之，未見佛性亦應見之」。二就十住菩薩設難，若未聞時已有聞者，「云何說言十住菩薩雖見佛性，未得明了」。三就佛設難，若未聞時已有聞者，「如來本昔從誰得聞」。若有聞處，「何故如來於《阿含》中說言無師」。後中初言「若不聞不聞」審定如來未聞之時令無聞性，名不聞不聞。下就設難，難意如何？若佛如來本未聞時一向無聞，後得菩提及見佛性。一切眾生未聞之時亦無有聞，亦應同佛得成菩提見於佛性。一切眾生不得菩提不見佛性，可得宣說本無有聞。佛得菩提見佛性故明本有聞，本有聞故佛令聞時聞於先聞，非聞不聞。

Below, objections are raised, and the objections have three levels: First, raising an objection with regard to ordinary persons prior to the grounds: If, before having heard, they already possessed hearing, then 'all sentient beings, not yet possessing bodhi, should forthwith possess it; not yet having attained nirvāṇa, should also attain it; not yet having seen buddha-nature, should also see it.' Second, raising an objection with regard to bodhisattvas of the ten abodes: If, before having heard, they already possessed hearing, 'how can it be said that although bodhisattvas of the ten abodes see buddha-nature, they have not yet attained clear comprehension?' Third, raising an objection with regard to the Buddha: If, before having heard, he already possessed hearing, 'from whom did the Tathāgata originally hear it in the past?' If there was a place from which he heard it, 'why did the Tathāgata state in the Āgamas that he had no teacher?'
In the latter [part], the opening words, 'If one does not hear what is unheard,' definitively establish that when the Tathāgata had not yet heard, he was made to lack the nature of hearing, which is termed 'not hearing what is unheard.' Below, an objection is raised; what is the meaning of the objection? If when the Buddha, the Tathāgata, originally had not yet heard, he entirely lacked hearing, yet later attained bodhi and saw buddha-nature, then all sentient beings when they have not yet heard likewise lack hearing, and they should also, like the Buddha, attain the realization of bodhi and see buddha-nature. If all sentient beings do not attain bodhi and do not see buddha-nature, one could then declare that originally they had no hearing. Because the Buddha attained bodhi and saw buddha-nature, it is clear that originally he had hearing; and because he originally had hearing, when the Buddha makes [them] hear, they hear what was previously heard, not hearing what was unheard.