成唯識論述記 5.144

5.144

述曰：五識緣五塵，五識言緣外；末那緣五塵，亦應緣外境，如何可言「緣內起我」？若緣內色名緣內者，五亦應然，等流境故。

[The Commentary states:] The five consciousnesses take the five sensory dusts (viṣaya) as cognitive objects, and the five consciousnesses are said to take external objects as cognitive objects; if manas took the five sensory dusts as cognitive objects, it should also take external realms as cognitive objects; how could it be said to 'rely on the internal to give rise to a self'? If taking internal matter as cognitive object is called taking the internal as cognitive object, the five should also be so, because they are realms of uniform flow (niṣyanda).