Abū Saʿīd b. Abī al-Khayr, Faḍl Allāh b. Aḥmad b. Muḥammad b. Ibrāhīm Mayhanī (1 Muḥarram 357–4 Shaʿbān 440/7 December 967–12 January 1049), was a famous mystic from Mayhana (also Mihna or Mīhna) in Khurāsān. Mayhana was a well-known village in Khurāsān, located between Sarakhs and Abīward (q.v.). Some historians have connected him to Abīward since Mayhana was one of its dependencies (Faṣīḥ, 2/167). His name is given by some writers as Faḍl (see al-Ṣarīfīnī, 623; al-Samʿānī, al-Ansāb, 12/537), but is also record…