成唯識論演祕 6.165

6.165

釋曰：若以二智不執外境，二智所緣不離識故，唯識自成故不待說。無色，經部心不執外，彼界唯識不說應成，對彼應言二界唯識。

Explanation: If, because the two knowledges do not grasp external objects, and the objective referents of the two knowledges are not separate from consciousness, vijñapti-mātra is established on its own and requires no mention; then in the formless realm, the Sautrāntika's mind does not grasp external things, so vijñapti-mātra in that realm would be established without being stated, and against them one ought to say "two realms are vijñapti-mātra."