成唯識論述記 2.484

2.484

述曰：且三無為，非如前二，世共知有，不同第三。比作用了如眼、耳等，故知定無。量云：汝宗所立三種無為，應離色等無別實性；前三法不攝故，或非世共知及無用故；如龜毛等。然我真如，非全離於色、心等有，無不定過。又應簡別汝等無為，非真實有；以無用故；如兔角等。

The Commentary states: The three unconditioned dharmas are not like the first two, commonly known to the world to exist; nor are they like the third, known through functional efficacy like the eye, ear, and so forth; hence we know they are definitively non-existent. The syllogism is: The three unconditioned dharmas established by your school should have no separate real nature apart from form and so forth; because they are not subsumed under the previous three dharmas, or because they are not commonly known to the world and lack function; like the hair of a turtle and so forth. But our tathatā does not exist completely apart from form, mind, and so forth, so there is no fallacy of inconclusiveness (anaikāntika). Furthermore, one should qualify [the proposition]: your unconditioned dharmas are not truly real; because they lack functional efficacy; like a rabbit's horn and so forth.