大般涅槃經集解 2.93

2.93

案僧亮曰：能備上德，非積行不就也。解未解者，向說誓時，今說行時也。僧宗曰：向明現在行，今明過去行。

Sengliang comments: To be fully endowed with the superior virtues above cannot be accomplished without accumulated practices. 'Understanding what has not been understood' refers back to when the vow was made; now it speaks of when the practice is carried out. Sengzong says: Previously it clarified present practice; now it clarifies past practice.