大般涅槃経
According to the "Mahāyāna Mahāparinirvāṇa Sūtra", a Mahayana sutra giving Gautama Buddha's final teachings, the Buddha insisted that his followers should not eat any kind of meat or fish. Even vegetarian food that has been touched by meat should be washed before being eaten. Also, it is not permissible for the monk or nun just to pick out the non-meat portions of a diet - the whole meal must be rejected.