17.13 They say that sacrifice is Tamasa, which is bereft of the authority of injunction of Brahmanas of learning and good conduct as 'Do this sacrifice,' which is 'Asrstanna' viz., which uses offerings (materials) not sanctioned by the Sastras; which is performed without recitation of hymns; and which is bereft of gifts and faith. Now, to explain the threefold division of austerities according to their source in the Gunas, Sri Krsna describes their differences in respect of the body, speech and mind: