The Buddha and Tolerance

Not only the freedom of thought, but also the tolerance allowed by the Buddha is astonishing to the student of the history of religions. Once in Nalanda a prominent and wealthy householder named Upali, a well-known lay disciple of Nigantha Nataputta (Jaina Mahavira), was expressly sent by Mahavira himself to meet the Buddha and defeat him in argument on certain points in the theory of Karma, because the Buddha's views on the subject were different from those of Mahavira. Quite contrary to expectations, Upali, at the end of the discussion, was convinced that the views of the Buddha were right and those of his master were wrong. So be begged the Buddha to accept him as one of his lay disciples (Upasaka). But the Buddha asked him to reconsider it, and not to be in a hurry, for 'considering carefully is good for well-known men like you'. When Upali expressed his desire again, the Buddha requested him to continue to respect and support his old religious teachers as he used to.

---What the Buddha Taught, by Walpola Rahula---