俱舍論疏 16.25

16.25

論「又身語業至故名牟尼」，第二釋也。身、語二業有無表故，名為遠離。意業非遠離故，不名牟尼。

On the text, "Furthermore, bodily and vocal karma [...] therefore they are called silence": This is the second explanation. Because bodily and vocal karmas have unmanifest [form] (avijñapti), they are called abstention. Because mental karma is not an abstention, it is not called silence.