大般涅槃經集解 54.117

54.117

案僧亮曰：二乘比之於凡為樂，方之菩薩為苦。於此二間，情以為足，故云作中道想也。僧宗曰：從苦法忍至緣一覺，以其不能安生死以化物，說之為苦；以其解苦性空，於凡夫為勝，亦小小化物，故謂苦樂行也。

Sengliang states: The two vehicles, compared to ordinary persons, are bliss; compared to bodhisattvas, they are suffering. Between these two, their sentiments take it to be sufficient; therefore it is said, ‘they form the conception of the middle way’. Sengzong states: From the stage of patience with the truth of suffering (duḥkhe dharmajñānaksānti) up to the solitary awakened ones, because they cannot find peace in saṃsāra to transform beings, it is spoken of as suffering; because they understand that the nature of suffering is empty, they are superior to ordinary persons and also somewhat transform beings, hence it is called the practice of suffering and bliss.