俱舍論記 13.85

13.85

「又若無無表至語等無故」者。此是第六八道支證。若有無表，可說在定有彼正語、正業、正命，具八道支。若無無表，應無八道支，但應有五，以在定時正語等三皆無有故。

"Furthermore, if there were no uninformative [...] because speech and the rest do not exist": this is the sixth proof from the eight path-factors. If there is the uninformative, it can be said that while in meditative concentration there are right speech, right action, and right livelihood, fully possessing the eight path-factors. If there were no uninformative, there should be no eight path-factors, but only five, because while in meditative concentration, right speech and the other three are entirely absent.