大般涅槃經集解 2.53

2.53

案僧亮曰：心為苦樂之本。眾生厭苦，不離苦因，為煩惱所惑，不得自在；今無苦因，所以自在也。

Sengliang states: The mind is the root of suffering and bliss. Living beings loathe suffering but do not part from the causes of suffering; deluded by afflictions, they cannot attain mastery. Now having no cause of suffering, they therefore have mastery.