大般涅槃經集解 46.112

46.112

案僧亮曰：第三難。若是可得者，則是無常也。寶亮曰：凡有法者皆是無常。佛昔云「三乘聖人若有涅槃」，以此義故，應是無常也。

Sengliang notes: The third objection. If it can be attained, then it is impermanent. Baoliang says: All things that exist are impermanent. In the past, the Buddha said, 'If the holy ones of the three vehicles have nirvāṇa...'; by this reasoning, it should be impermanent.