Abū Saʿīd Abū'l-Khayr or Abusa'id Abolkhayr, also known as Sheikh Abusaeid or Abu Sa'eed, was a famous Persian Sufi and poet who contributed extensively to the evolution of Sufi tradition. December 12, 967 – January 18, 1049; died at 81. Alive at the same time as Avicenna, William the Conqueror, Leif Erikson, Anselm of Canterbury, and Murasaki Shikibu. Wiki link