俱舍論記 5.22

5.22

「論曰至如堰江河」者，釋前兩句。若生無想有情天中，有不相應行異熟果法，能令未來心，心所滅，名為無想。此法體性是實有物，所以能遮未來心、心所法，於五百劫令暫不起，如堰江河，故知實有。恐濫草等，故言有情。

As for "The treatise says ... like damming a river": this explains the previous two lines. If one is born among the non-ideational sentient beings' heaven, there is an unassociated conditioned phenomenon (citta-viprayukta-saṃskāra) that is a maturation-fruit dharma, able to cause future minds and mental factors to cease; this is named 'non-ideation.' The essential nature of this phenomenon is a real entity, which is why it can obstruct future minds and mental factors, preventing them from arising temporarily for five hundred kalpas, like damming a river; therefore one knows it is real. Fearing that it might be confused with grass and the like, it says 'sentient beings.'