瑜伽論記 16.283

16.283

不證不還者，泰、景等云：初果練根，何故不得不還果者，即由二因，一離欲界時，是三障中障礙處難對治故，名治難得。二所得道果定等，功德廣大故，亦可無為果眾多故。論主不說一來轉根得不還者，以度欲界是難處故，必不得果。

Regarding 'not realizing the non-returner': Tai, Jing, and others say: 'Why does a stream-enterer who refines their faculties not attain the non-returner fruit? It is due to two causes: First, when separating from the desire realm, this obstacle among the three obstacles is a state difficult to antidote, hence it is called difficult to obtain an antidote. Second, because the virtues of the fruits of the path, concentrations, and so forth to be obtained are vast; it may also be because the unconditioned fruitions are numerous. The treatise master does not state that a once-returner who transforms their faculties attains the non-returner fruit because transcending the desire realm is a difficult place, so they definitely do not attain the fruit.'