Madhvaon Brahma Sūtra 3.1.20

Further, that the lowermost hell of darkness is a place of absolute misery is established by the statement in the Pâdma of Brahma’s direct perception, which is, “ Through the grace of the Lord Narayana, with the eye of wisdom, Brahma, the four-paced directly saw the three classes of beings, those who are for ever immersed in absolute misery and deprived of all pleasure, those in great num- bers who are eternally of mixed character, (and) those from whom all misery or pain has been banished and on whom unmixed enjoyment of bliss is for ever bestowed.”