大乘起信論別記 1.118

1.118

第四「智識」者，是第七識，上六相中初智相也。愛果名染淨法，分別彼法計我我所故，言「分別染淨法」也。

Fourth, the 'cognitive consciousness' is the seventh consciousness; it is the first, the characteristic of cognition, among the six characteristics above. Karmic retribution that is liked or disliked is called defiled and pure dharmas; discriminating those dharmas and conceiving a self and what belongs to a self, it is said to 'discriminate defiled and pure dharmas.'