俱舍論記 25.37

25.37

「經言苾芻至非阿羅漢」者，答。經云：無漏聖慧斷惑名為實斷。阿羅漢果唯聖慧斷，既言實斷，明知不退。經誡有學應不放逸，恐學退故。非說阿羅漢應不放逸，明知不退。

Regarding 'The sūtra says, "Monks… not an arhat"': this is the answer. The sūtra says: Abandoning defilements through uncontaminated noble wisdom is called real abandonment. The fruit of arhatship is abandoned solely by noble wisdom; since it is called real abandonment, it is clearly known that there is no falling away. The sūtra admonishes those in training that they should be diligent, fearing that those in training might fall away. It does not say that arhats should be diligent, so it is clearly known that they do not fall away.