俱舍論記 7.110

7.110

「勢力劣故至可能生彼」者，答。異熟生心勢力劣故，非作功用所引發故，樂作功用引發工巧、威儀轉故，所以此三不能順起加行善心。出心不由功用轉故，所以從加行無間能生彼三。

Regarding "Because their power is inferior ... can produce them": the answer. Because the power of the mind born of maturation is inferior and is not induced by exertion, whereas the arts and crafts and deportment proceed through the wish to make an effort and induce them, these three cannot concordantly produce an acquired good mind. Because emerging from a mind does not proceed through exertion, therefore immediately following acquired [goodness], those three can be produced.