俱舍論疏 25.20

25.20

論「退法種性至通三界皆有」，明五種姓名據容有，非即如名定有退等。三界具有六種種姓，而於上界無退練根。

On the Śāstra's statement: "The lineage of the liable to fall away ... are all present throughout the three realms": This explains that the designations of the five lineages are based on possibility, and do not mean that falling away and so forth definitely occur in accordance with their names. In all three realms, all six lineages are present, yet in the higher realms there is neither falling away nor the training of faculties.