俱舍論疏 6.143

6.143

「論曰至異熟法故」，出異熟因體也。異熟法者，如下廣釋。三性之中善、不善唯是異熟因也，無記唯非異熟因也。善有二種，有漏是異熟因，無漏非異熟因。

The treatise says: "From [...] down to [...] because they are phenomena of maturation." This identifies the intrinsic nature of the maturation cause. What are "phenomena of maturation" is explained in detail below. Among the three natures, the wholesome and the unwholesome alone are maturation causes; the indeterminate alone is not a maturation cause. Of the wholesome there are two kinds: that with outflows (sāsrava) is a maturation cause; that without outflows (anāsrava) is not a maturation cause.