成唯識論演祕 6.412

6.412

今依第八緣境而說可有本質，非一切識皆要有質，如意緣空便無質故。

Now, speaking in terms of the eighth consciousness taking objects, it may have a mūla-dharmin; it is not that all consciousnesses must necessarily have a mūla-dharmin, just as when the mental consciousness takes emptiness as object, there is no mūla-dharmin.