成唯識論述記 2.714

2.714

言異熟者，如前已釋，異熟習氣，唯依士釋。果是異熟，因名習氣，故第八唯果變而非因，種子因變而非果，現七識亦因亦果能變，前六識中異熟無記心等，同第八識唯果能變，非能熏故，至下當知。

Regarding "maturation," it has already been explained above; "maturation vāsanā" is exclusively a tatpuruṣa compound. The fruit is maturation, and the cause is named vāsanā; therefore, the eighth is solely a transformation of fruit and not of cause, whereas seeds are transformations of cause and not of fruit. The active seven consciousnesses are transformations of both cause and fruit; among the first six consciousnesses, minds of maturation indeterminacy and so forth are, like the eighth consciousness, solely transformations of fruit, because they cannot perfume, as will be understood below.