俱舍論疏 23.175

23.175

論「此預流名至故名預流」，答也。遍得一切是次第人，此初得果建立此名。一來、不還非定初得，若超越者即是初得，若次第者即非初得，故名預流。

On the passage of the treatise from "This name 'stream-enterer'" to "therefore called a stream-enterer": This is the answer. Attaining all [fruits] across the board applies to the person of gradual progress; this name is established for their initial attainment of the fruit. The once-returner and non-returner are not necessarily attained initially: if one is a leaper, they are attained initially; if one is a gradualist, they are not attained initially. Therefore [the initial fruit of the gradualist] is called a stream-enterer.