俱舍論記 24.9

24.9

「頌中但說至故不具說」者，此釋頌中不說第二緣所以。三緣之內頌中但說初後緣者，預流果後說更進斷三、四品惑，成能治彼諸無漏根，義准已成故不具說。

Regarding "In the verse, only [the first and last conditions] are stated … hence they are not fully stated": this explains the reason why the second condition is not stated in the verse. Among the three conditions, only the first and last conditions are stated in the verse because, having attained the fruit of Stream-Enterer, it is said that one further advances to abandon three or four grades of afflictions, which implicitly establishes by logical implication that one accomplishes the anāsrava faculties that counteract them; therefore, it is not stated in full.