Who is Abu Yazid al-Bistami, and what is the story of the "hundred and one questions" narrated about him?

Abu Yazid al-Bistami is Tayfur ibn Isa, one of the Sufi masters. He attained knowledge through hunger and abandoning pleasures. He said: "If you see a man who has been given miracles to the extent that he rises into the air, do not be deceived by him until you see how you find him concerning commands and prohibitions, safeguarding boundaries, and adhering to the Sharia." He passed away in the year 261 AH. Extravagant statements (shatahat) have been narrated about him, which some jurists and Sufis interpreted as having been uttered in a state of ghaiba (absence or trance), while others declared him an innovator and considered them innovations indicating a corrupt belief. As for the story of the hundred questions, there is no knowledge of it.