瑜伽論記 22.154

22.154

次釋三受皆苦，有三番重釋，第一番云：樂受，變壞故苦；一切苦受，生住故苦者，此文分明說苦受生時苦住苦，故苦苦，非苦樂受捨受，念念滅壞釋行，行帶麁重不得自在名苦苦，體是無常滅壞法故說之為苦。

Next, he explains that all three feelings are suffering. There are three rounds of repeated explanation. The first round states: "Pleasant feelings are suffering because of change and deterioration; all painful feelings are suffering because of their arising and remaining." This text clearly states that when a painful feeling arises, there is suffering, and while it remains, there is suffering; thus it is the suffering of suffering. Neither-painful-nor-pleasant feelings, namely equanimous feelings, which perish and deteriorate moment by moment, explain conditioning; conditioning carries coarseness and heaviness and does not attain self-mastery, which is called the suffering of suffering, and because its substantial nature is an impermanent, perishable phenomenon, it is spoken of as suffering.