瑜伽師地論略纂 9.21

9.21

論解第三靜慮中云「第三靜慮以下，無如此樂及無間捨」者，已下有樂，體是喜，適悅身心為樂。今第三靜慮中，適悅心亦名樂，以樂極故，故言下地無是樂。下地內行中雖有捨，不別顯名；又有間故，非無間捨，故言無。非有間捨亦無名無捨也。

Regarding the śāstra's explanation of the third dhyāna, which states: "Below the third dhyāna, there is no such bliss or uninterrupted equanimity": below this there is bliss whose essence is joy; the gladdening of body and mind is bliss. Now in the third dhyāna, the gladdening of mind is also called bliss; because bliss is supreme, it says that the lower stages have no such bliss. Although there is equanimity in the internal practice of the lower stages, it is not distinctly designated with that name; furthermore, because it is interrupted, it is not uninterrupted equanimity, hence it says there is none. It is not that interrupted equanimity is also absent so as to be called having no equanimity.