成唯識論述記 4.205

4.205

述曰：量云：色、不相應，理非染淨內法所熏，亦不能持種，此中二宗；因云：非心性故；喻云：如聲、光等。內法所熏，簡苣勝等色，為外法熏故。此中不取堅性為法，故知性不堅住。非宗之法，即是因也。總配別配色、不相應，因、宗可解。

The Commentary states: The inference says: Form and unassociated [formations] are by reason not perfumed by internal defiled and pure dharmas, nor can they hold seeds (here are two probanda); Reason: because they are not of the nature of citta; Example: like sound, light, and so forth. 'Perfumed by internal dharmas' excludes form such as sesame seeds, because they are perfumed by external dharmas. Here, 'firm nature' is not taken as the probandum, so we know that 'nature not firmly persisting' is not a property of the probandum, but is rather the reason. Comprehensively and separately matching form and unassociated [formations], the reason and the thesis can be understood.