俱舍論疏 22.87

22.87

論「然觀樂時至觀樂為苦」，釋伏難也。若自相是樂、異門是苦，何故世尊教觀異門，不觀自相？答云：若觀自相增貪等故，觀異門時能得解脫，故令觀苦不令觀樂。

On the Śāstra's statement, "However, when observing pleasure... observes pleasure as suffering": This explains an implicit objection. If its intrinsic characteristic is pleasure and the figurative approach is suffering, why did the World-Honoured One teach observing the figurative approach and not observing the intrinsic characteristic? The reply says: Because observing the intrinsic characteristic increases greed and so forth, whereas when observing the figurative approach one is able to attain liberation; therefore, he instructed the observation of suffering and did not instruct the observation of pleasure.