成唯識論演祕 2.877

2.877

即此習氣有因有果，論中但舉習氣之因以彰其體，不舉其果而辨體也。

Namely, these karmic impressions (vāsanā) have both cause and fruit; the treatise merely adduces the cause of the vāsanā to reveal its substance, not adducing its fruit to analyze its substance.