大般涅槃經集解 5.32

5.32

Daosheng states: Taking what the Buddha taught as proof, the real principle is fundamentally unalterable. It is only known when one attains awakening through the teacher. Since the principle taught cannot alter, one clearly knows that awakening to it also serenely endures permanently.
Sengliang states: What all Buddhas take as their teacher is the dharma of nirvāṇa. If the Buddha were impermanent, the Dharma would also be impermanent; hence it is said that no one would believe the true Dharma he taught either.
Huilang's distinct commentary states: This is the fourth parable. The reason the family members no longer loved this child was due to the deluded pronouncement of a trustworthy physiognomist. If people hear you say the Buddha is impermanent, since you are a trustworthy person, they might also not believe on your account.