成唯識論述記 6.191

6.191

述曰：如前已說苦根在意，故後餘四亦得相應。此就他宗設說五識無欲等，故說自意識有苦根義。

The Commentary states: As was already explained before that the faculty of suffering exists in the mental consciousness, the remaining four [factors] can also associate with it. This is said by adopting the other school's tentative claim that the five consciousnesses lack desire and the like, thereby explaining one's own position that the mental consciousness has the faculty of suffering.