成唯識論述記 8.412

8.412

述曰：然此病法非如老法，雖非必定一切有情皆悉有之，遍諸趣界，故立為支，病不定遍，故不立也。問：何以得知諸色無色亦有老耶？

The Commentary states: However, this phenomenon of sickness is not like the phenomenon of aging. Although [aging] is not definitely present in all sentient beings without exception, it is pervasive across all destinies and realms, and is therefore established as a factor. Sickness is neither definite nor pervasive, so it is not established. Question: How is it known that the form and formless [realms] also have aging?