Amagandha sutta (Sutta nipata, culavagga)
In this sutta the Buddha Kassapa refutes the idea of the ascetic Tissa that by abstaining from eating meat etc. one is pure..
"When men are rough and harsh, backbiting, treacherous, without compassion, haughty, ungenerous and do not give anything to anybody; this is uncleanness and not the eating of flesh."
"Neither abstaining from flesh or fish, nor fasting, nor nakedness, nor tonsure, nor matted hair, nor dirt, nor rough skins, nor the worshipping of the fire, nor the many immortal penances in the world, nor hymns, nor oblations, nor sacrifice, nor observance of the season, purify a mortal who has not conquered his doubt."