俱舍論記 28.97

28.97

「此定遠離至如河有浪」者，經部師答。此第二定能遠離彼尋、伺鼓動，定體相續清淨寂靜轉，名為內等淨。若有尋、伺鼓動，此定相續不清淨、不寂靜轉，如河有浪，不名內等淨。

Regarding the passage "This absorption is free from... like a river having waves": The Sautrāntika master answers: This second absorption is able to be free from the agitation of that investigation and scrutiny; the continuity of the absorption's entity operates purely and tranquilly, and is called internal serene clarity. If there were the agitation of investigation and scrutiny, the continuity of this absorption would operate impurely and without tranquility, like a river having waves, and would not be called internal serene clarity.