俱舍論疏 3.178

3.178

論「若成眼根至捨樂喜根」，釋定成五。成眼等必依身故，成喜必成樂故，所以定成五根。

On the Śāstra's statement: 'If one possesses the eye faculty up to equanimity, pleasure, and joy faculties,' this explains the definite possession of five. Because the possession of the eye and the others must rely upon the body, and because possessing joy necessarily entails possessing pleasure, one therefore definitely possesses five faculties.