俱舍論記 10.226

10.226

「正邪定餘至可成二故」者，釋不定性。正、邪定餘所有諸法名不定性，彼待善緣可成正定性，彼待惡緣可成邪定，非定屬一，故名不定。諸有情類成就此三差別不同，名三聚異。故《集異門足論》第四云「云何邪性聚？答：五無間業。云何正性定聚？答：學、無學法。云何不定聚？答：除五無間業，餘有漏法及無為也。」

"What is other than correct and wrong certitude […] can become either of the two": this explains indeterminate nature. All dharmas other than correct and wrong certitude are called indeterminate nature: dependent on wholesome conditions, they can become of the nature of correct certitude; dependent on unwholesome conditions, they can become of wrong certitude; they do not determinately belong to one, hence they are called indeterminate. The differences in sentient beings' possession of these three are called the distinctions among the three collections. Thus the Saṅgītiparyāya fascicle 4 says: "What is the collection of wrong nature? Answer: The five immediate karmas. What is the collection determinate in correct nature? Answer: The dharmas of the trainee (śaikṣa) and the non-trainee (aśaikṣa). What is the indeterminate collection? Answer: Excluding the five immediate karmas, the remaining sāsrava dharmas and asaṃskṛta dharmas."