大般涅槃經集解 16.78

16.78

案僧亮曰：求常以淨戒為本。先令讀律，已犯重禁。於己是苦名毒，治其之罪名藥也。

Sengliang comments: Seeking permanence takes pure precepts as its foundation. First making him recite the Vinaya, [he discovered that] he had already violated major prohibitions. Because it is suffering for oneself, it is called poison; because it cures one's transgressions, it is called medicine.