大般涅槃經集解 15.109

15.109

案智秀曰：所以初一乃至八者，其分外解，可應有無量。但既不入可依之限，故不錄也。今舉其可名得不退者，言一分也。

Zhixiu comments: The reason it goes from the initial one up to eight is that understanding outside of those parts could be immeasurable. But since it does not fall within the limit of what can be relied upon, it is not recorded. Now, pointing to that which may be named as attaining non-retrogression, it speaks of 'one part.'