俱舍論記 25.24

25.24

「何緣定無退先果者」者，此下明諸部諍論四果退不退。若依說一切有部，初果不退，後三果容退，如前具說。問：何緣定無退先果者？

Regarding 'For what reason is there definitely no falling away for one who has an initial fruit?': from here down, the dispute among the various schools concerning falling away and not falling away from the four fruits is clarified. If one relies on the Sarvāstivāda, the first fruit is not fallen away from, while the latter three fruits admit of falling away, as explained in detail previously. The question is: For what reason is there definitely no falling away for one who has an initial fruit?