成唯識論述記 7.563

7.563

述曰：此論主答：誰說他心非自識境，許有他心亦為我境，所以有他心智，但不說他心是自心親所緣，故成唯識。

The Commentary states: This is the author's reply: Who says another's mind is not an object of one's own consciousness? We accept that another's mind exists and is also an object for me, which is why there is knowledge of another's mind; but we do not say that another's mind is a direct conditioned object of one's own mind, and therefore consciousness-only is established.