俱舍論疏 3.143

3.143

論「信等五根至及無漏故」，釋信等五根，非染污故不通見斷，通有漏故是修所斷，通無漏故亦非所斷。

The commentary states: "The five faculties of faith, etc. [...] and undefiled." This explains the five faculties of faith, etc.: because they are not defiled, they do not extend to being abandoned by seeing; because they extend to being defiled, they are abandoned by meditation; because they extend to being undefiled, they are also not to be abandoned.