瑜伽論記 14.372

14.372

若言不滅，便起行相者，不滅即常，非有為行。量云：汝所立業應是無為，以不滅故，如虛空等。

As for 'if it is said not to cease, then the characteristic of conditioned action arises': not ceasing is precisely permanence, not a conditioned action. The inference is: 'The karma established by you should be unconditioned (thesis), because it does not cease (reason), like empty space and the like (example).'