成唯識論述記 5.480

5.480

述曰：無學無此識，第八應無依。若許八無依，違比量過。汝無學位第八必有現行俱有依；是識性故；如餘七識。彼師許第七以第八為依故。

The Commentary states: If the aśaikṣa lacks this consciousness, the eighth would have no basis. If one admits that the eighth has no basis, there is the fault of contradicting the inference. In your aśaikṣa stage, the eighth consciousness must have an actively present, co-arising support; because it is of the nature of consciousness; like the other seven consciousnesses. For that master admits that the seventh takes the eighth as its support.