成唯識論演祕 5.74

5.74

釋曰：謂信等五、三無漏根及意、喜、捨。有云：除意取樂，理實應說有十二根，亦有意故，而不說者意根通顯八識自性，未至地中唯有第六，故略不說。

Explanation: Namely, the five beginning with faith, the three anāsrava faculties, and the mental faculty, joy, and equanimity. Some say: Excluding the mental faculty and taking pleasure, in principle it should actually be said that there are twelve faculties, because there is also the mental faculty; the reason it is not stated is that the mental faculty broadly indicates the self-nature of the eight consciousnesses, whereas in the unarrived stage there is only the sixth, and so it is omitted for brevity.