Sath, an apparently blasphemous utterance made by a Sufi during a spiritual ecstasy, is a controversial term as there is no consensus on its definition. The purpose of this paper is to study sath in the works of 'Attar. In 'Attar, sath may be studied from tow points of view: its surface form, which mayor may not be against religion, and its deep meaning, which, in principle, cannot be against religion, but which needs to be interpreted. Words uttered in defense of Iblis, for example, provide a good example of sath, which frequents in 'Attars' works. Sathiyyat, in the works of 'Attar, appear in tow forms: some sath are utterances made by great Sufis, some are blasphemous utterances made by wise Sufis who pretend to be lunatics. It seems that these latter Sufis represent the hidden personality of 'Attar himself, who invents them to talk for him without his words being criticized by devout ascetics and cruel rulers. These apparent lunatics are able to utter their strong protest against not only the oppression of unjust rulers but the creation of the universe as well.