大般涅槃經義記 7.105

7.105

第二難中論其難辭，將下類上明佛不定。難意有三：一明佛不定，破前佛有常、樂、我、淨；二明佛不定，欲使如來述己所問，顯成如來不畢竟滅，故下文中德王領解「如是如是，誠如聖教，一切諸法悉皆不定」，以不定故，如來亦不畢竟涅槃；三明佛不定彰闡提等當無所得，成現無性，故下文言「若無常等，云何說言一闡提等當得涅槃」。

Regarding the phrasing of the challenge in the second challenge, it takes the lower to analogize with the higher to explain that the Buddha is indeterminate. The intention of the challenge has three aspects: First, by explaining that the Buddha is indeterminate, it refutes the previous [assertion that] the Buddha possesses permanence, bliss, self, and purity. Second, by explaining that the Buddha is indeterminate, it aims to cause the Tathāgata to confirm his own question and clearly establish that the Tathāgata does not undergo ultimate extinction; thus, below in the text, King of Virtue grasps and understands: "So it is, so it is, truly as the holy teaching says, all phenomena are entirely indeterminate"; because they are indeterminate, the Tathāgata also does not enter ultimate nirvāṇa. Third, by explaining that the Buddha is indeterminate, it makes clear that icchantikas and the like will in the future attain nothing, thereby establishing that they currently lack the nature; thus the text below states: "If there is no permanence and so forth, how can it be said that icchantikas and the like will in the future attain nirvāṇa?"