成唯識論述記 2.182

2.182

述曰：非但意業以思為體，身、語二業體復是思，故論言亦。又業道實體，唯思是也，假名業道通身、語二，以實思業亦二假道，故論言亦。

The Commentary states: Not only does mental karma have volition as its entity, the entity of the two karmas of body and speech is also volition; hence the treatise says "also". Furthermore, the real entity of the paths of karma is solely volition; the nominal designation "path of karma" extends to the two of body and speech, and since the real karma of volition is also the two nominal paths, the treatise says "also".