成唯識論述記 5.166

5.166

述曰：且於世事，無一念心中有斷、常二境，起二別執俱轉義故。前後可然，此即舉事，如斷、常者二境，非一心中起彼二別執。如何我、我所二境，或五蘊多境，而起二別執？非執可然，佛真俗智一用義分，彼非是執，不堅著故；執則不然，堅著境故名為執故；故無此事。人、法二執非別所緣、行相不返，故得俱有。

The Commentary states: Now, in mundane affairs, there is never a single moment of mind in which the two objects of annihilation and permanence exist such that two separate grasps could operate together. Occurring sequentially would be permissible, and this is just citing an example: as with the two objects of annihilation and permanence, two separate grasps cannot arise within a single mind. How could two separate grasps arise with respect to the two objects of self and mine, or the many objects of the five aggregates? If it were not a grasp, it could be so: the Buddha's real and conventional wisdoms are differentiated conceptually within a single function; those are not grasps, because there is no tenacious clinging. Grasps are not like that, for tenacious clinging to an object is precisely why it is called a grasp; hence this state of affairs does not occur. The two grasps—of person and phenomena—do not have different objective supports, nor do their ākāras run contrary to each other; therefore, they can coexist.