成唯識論述記 8.310

8.310

述曰：以三種望果談其親疎。今此三中，惑、業二種非異熟性，與果異性，但增上緣，助生苦故，但為勢引，非正親生。若苦種子與生死苦為正因緣，以能辨體親生苦故。

The Commentary states: Looking from the three seeds to the fruit, their direct or indirect relationship is discussed. Now, among these three, afflictions and karma are not of the nature of maturation and are of a different nature from the fruit; they are only superior conditions, assisting the arising of suffering, acting only by inducing power, and are not directly and proximately productive. But the seeds of suffering are the true direct causes (hetupratyaya) for the suffering of birth-and-death, because they can differentiate the substance and directly produce suffering.