俱舍論記 14.48

14.48

「論曰至勢微劣故」者，釋初三句。住別解脫，未捨戒來，恒成現世。初剎那後第二剎那已去亦成過去。第二句中「未捨」之言，遍流至後不律儀等。無有欲界散地無表有成未來，不隨心色，非心一果，勢微劣故。即由此理，亦不能成前生中戒。

Regarding "The commentary states... because their power is slight and inferior": this explains the first three lines. One who abides in prātimokṣa, so long as they have not yet relinquished the precepts, constantly possesses the present. From the second moment onward after the initial moment, one also possesses the past. The words "not yet relinquished" in the second line extend universally through to the subsequent non-discipline and so forth. There is no unmanifest form of the scattered plane of the desire realm that is possessed in the future, because it is a form that does not conform to the mind, is not the single fruit of the mind, and its power is slight and inferior. Precisely for this reason, one also cannot possess the precepts from a past life.