俱舍論疏 23.80

23.80

論「失退二捨至失不必然」，第十三明二捨同異。失謂生上地，及捨眾同分。生上地命終，心定無染也。捨眾同分捨不定，或染心命終、或不染心命終。若退捨必起染心，由此故言退必起過。失不必然，不必然言顯不定也。既捨得名退，故此二退非得為性。

On the Śāstra's statement: "Between the two abandonments of loss and retrogression [...] loss is not necessarily so": the thirteenth [section] clarifies the similarities and differences between the two abandonments. Loss refers to being born into a higher bhūmi and abandoning nikāya-sabhāga. When dying to be born into a higher bhūmi, the mind is definitely undefiled. In abandoning nikāya-sabhāga, abandonment is indefinite: one may die with a defiled mind or with an undefiled mind. If it is abandonment by retrogression, one definitely gives rise to a defiled mind; because of this, it is said that retrogression definitely gives rise to a fault. Loss is not necessarily so; saying 'not necessarily so' indicates that it is indeterminate. Since the abandonment of attainment is called retrogression, these two retrogressions have non-attainment as their nature.