大乘起信論義記 3.210

3.210

自然而有不思議業種種之用，即與真如等遍一切處，又亦無有用相可得。何以故？謂諸佛如來，唯是法身智相之身，第一義諦無有世諦境界，離於施作，但隨眾生見聞得益，故說為用。

"Spontaneously there are the manifold functions of inconceivable activity, which are equal to tathatā and pervade all places; yet there are also no marks of function to be obtained. Why is this? Because all Buddhas and Tathāgatas are bodies of only the marks of wisdom of the dharmakāya; in the ultimate truth there are no realms of worldly truth, and they are free from deliberate action; only in accordance with sentient beings seeing and hearing do they obtain benefit, and therefore it is spoken of as function."