俱舍論記 15.87

15.87

「二由得戒至勢力強故」者，第二由得戒捨，謂得別解、靜慮二戒，惡戒便捨。由內因、外緣故，得律儀時惡戒便斷。以善、惡戒其性相違必無俱起，善戒於中初起增盛勢力強故，能捨惡戒。問：三律儀中何故不說無漏律儀能捨惡戒？解云：於見道前必得定戒、捨彼惡戒。前已捨故，故不說彼道戒能捨。

"Second, through obtaining discipline [...] because its power is strong" means: second, it is relinquished through obtaining discipline, which means that upon obtaining the two disciplines of prātimokṣa and dhyāna, bad discipline is immediately relinquished. Due to internal causes and external conditions, when discipline is attained, bad discipline is immediately severed. Because wholesome and bad discipline are mutually contradictory in nature, they never arise together; among them, wholesome discipline is intensely surging and strong in power upon its initial arising, and is therefore capable of relinquishing bad discipline. Question: Among the three disciplines, why is it not said that anāsrava discipline can relinquish bad discipline? The explanation is: before the path of seeing, one must have attained concentration discipline and relinquished that bad discipline. Because it has already been relinquished previously, it is not said that the path discipline can relinquish it.