金光明經文句記 2.380

2.380

三、「智性」下，令比知大用。無知之智既冥法性，法性本用具足發現，現長現短皆名常壽，以全性故。經釋智性略大用者，以可解故。

Third, from 'Wisdom and nature...' onward, causing one to infer and know the great function. Since wisdom without knowing merges with the Dharma-nature, the fundamental function of the Dharma-nature manifests completely; manifesting long or manifesting short are both called eternal lifespan, because they are entirely the nature. That the sūtra's explanation of wisdom and nature abbreviates the great function is because it can be understood.