俱舍論疏 25.124

25.124

論「道依無色至觀增止減」，釋苦通行。《正理論》云「雖道非苦，苦受相應艱辛轉故亦名為苦，如依陸路乘馬等行。艱辛轉者，由此地中止、觀雖俱而增減故。此依地立苦、樂名也。」

On the Śāstra's "When the path relies on the formless … vipaśyanā increases and śamatha decreases": this explains painful progress. The Nyāyānusāra says: "Although the path is not painful, because it proceeds with hardship associated with painful sensation, it is also called painful, like traveling on an overland road riding a horse, etc. 'Proceeding with hardship' means that in this ground, although śamatha and vipaśyanā are both present, they increase and decrease unevenly. This establishes the names painful and pleasant based on the grounds."