Devedatta was the son of Suddhodana’s brother Suppabuddha and thus was the Buddha’s cousin. His name means ‘god-given.’ When the Buddha returned to Kapilavatthu for the first time after his enlightenment, several young sakyan men including Devadatta decided to become monks (Vinaya 2. 182). For some years Devadatta proved to be a good and diligent monk and in several places in the Tipitaka he is praised as such (Vinaya 2. 188). Gradually however, he came to feel that the Buddha was drifting too far from traditional ascetic practices and a good number of monks agreed with him. Confronting the Buddha on this issue, Devadatta insisted that he make several practices compulsory for all monks - (1) that they should live only in the forest, (2) that they never accept invitations to eat at devotees homes but live only by begging, (3) that they wear only rag robes, (4) that they live in the open not in a monastery, and (5) that vegetarianism be compulsory, instead of the 3 fold rule. Devadatta’s demands were refused and so he and his supporters separated from the Buddha and his disciples. This was the greatest crisis the Buddha had to face during his forty-year ministry. The Vinaya even claims that Devadatta actually tried to murder the Buddha on two occasions, although it is not certain whether this is true or just a later attempt to make him look as bad as possible (Vin.II,190-94). There is no more information about Devadatta in the Tipitaka itself, but tradition says his supporters eventually abandoned him and returned to the Buddha and that he later died discredited and alone.
Devadatta and Vegetarianism
Some teachers have used the list of Devadatta and the Buddha's refusal of it to point out that the Buddha did not require or even recommend vegetarianism. But what these teachers fail to recognize is the Buddha allowed monks to follow the rules or suggestions by Devadatta, if they wanted to. It was not forbidden to follow the list, if a monk or nun wanted to. The refusal of the Buddha to accept the complete list also does not mean that he disagreed with everything in the list.
The Buddha praised Kassapa doing some ascetic practices, some of them from the list of Devadatta (Samyutta Nikaya 16.5) which shows that the Buddha was not opposed to everything in the list. In another passage the Buddha said:
"I do not say householder, that all asceticism should be practiced; nor do I say of all asceticism that it should not be practiced" (Anguttara Nikaya 10.94).