俱舍論疏 18.71

18.71

論「唯餘百劫至法應如是」，明修時也。法應如是，減則不足，多則無用也。

The Śāstra states: "Only in the remaining one hundred kalpas [...] such is the nature of the Dharma." This clarifies the time of cultivation. Such is the nature of the Dharma: if it were less, it would be insufficient; if it were more, it would be useless.