大般涅槃經義記 7.107

7.107

上來一段明佛不定，自下第二就前不定難破常等。「云何不定」徵前起後，下對辯之。句前有五：一重明前闡提不定，若一闡提除謗法心則成佛道，故知不定，前所辯中闡提最下，故偏舉之，餘類可知；二以闡提不定類佛不定，「如來亦應入涅槃已還出不入」；三以佛不定類涅槃不定，若佛如是入已還出，涅槃之性則為不定；四以涅槃不定難破常等，「涅槃不定，當知無有常、樂、我、淨」；五「云何」下結以顯過，涅槃若無常、樂、我、淨，「云何佛說一闡提等當得涅槃」？

The above section explains that the Buddha is indeterminate; from here below is the second, which relies on the preceding indeterminacy to challenge and refute permanence and so forth. "How are they indeterminate?" introduces what follows by taking up what came before; below, it is addressed and discriminated. Before the clauses there are five points: First, re-explaining the previous indeterminacy of the icchantika: if an icchantika eliminates the mind that slanders the Dharma, they then realize the Buddha path, hence one knows they are indeterminate; in the previous discrimination the icchantika was the lowest, so they are singled out, and the rest can be known by analogy. Second, using the icchantika's indeterminacy to analogize with the Buddha's indeterminacy: "The Tathāgata also should, having entered nirvāṇa, re-emerge and not enter." Third, using the Buddha's indeterminacy to analogize with nirvāṇa's indeterminacy: if the Buddha in this way re-emerges after entering, the nature of nirvāṇa is then indeterminate. Fourth, using nirvāṇa's indeterminacy to challenge and refute permanence and so forth: "If nirvāṇa is indeterminate, one should know that it lacks permanence, bliss, self, and purity." Fifth, from "How" onward, concluding in order to reveal the fault: if nirvāṇa lacks permanence, bliss, self, and purity, "How can the Buddha say that icchantikas and the like will in the future attain nirvāṇa?"