大般涅槃經集解 7.124

7.124

案法瑤曰：執無常教，以為理極，此譬未信說常之時也。寶亮曰：譬〈哀歎品〉三勸三請。

Fayao says: Clinging to the teaching of impermanence and considering it the ultimate principle, this symbolizes the time when they did not yet believe in the expounding of permanence. Baoliang says: This symbolizes the three exhortations and three entreaties in the 'Grief and Lamentation Chapter'.