俱舍論記 22.44

22.44

「若諸苦受至住時苦」者，若諸苦受，由體成苦性。經言：苦受生時苦、住時苦，故名為苦，壞時樂故。《正理》釋經云「然薄伽梵契經中言：苦受生時、住時苦者，由彼苦受性是苦故。壞時樂者，苦受壞時設無樂受，由苦受息似樂顯現，故亦名樂。於相續息位立以壞名，故苦受息時名苦受壞。

Regarding "If painful feelings... are suffering when abiding": if they are painful feelings, they are suffering by nature through their very essence. The sūtra states: "Painful feelings are suffering when arising and suffering when abiding"; therefore they are called suffering, "because they are pleasure when undergoing destruction." The Nyāyānusāra explains the sūtra: "However, the Bhagavān said in the sūtra: 'Painful feelings are suffering when arising and when abiding' because that painful feeling is by nature suffering. 'They are pleasure when undergoing destruction' means that when painful feeling is destroyed, even if there is no pleasant feeling, its manifesting as a semblance of pleasure through the cessation of painful feeling is therefore also called pleasure. At the stage when the continuum ceases, the designation 'destruction' is established; therefore, when painful feeling ceases, it is called the destruction of painful feeling."