成唯識論述記 8.273

8.273

述曰：由此所說業果無斷，生死相續輪轉無窮，何假藉心外之緣，方得生死相續。此結答也。

The Commentary states: Because of what has been explained here, karma and fruit are uninterrupted, and the cycle of birth and death continues without end; why should it rely on conditions external to the citta in order to achieve continuation of birth and death? This concludes the answer.