Abū Bakr Aḥmad ibn Ḥusayn ibn ʿAlī ibn Mūsā al-Khusrawjirdī al-Bayhaqī, also known as Imām al-Bayhaqī, was a Sunni scholar widely known for being the foremost leading hadith master in his age, leading authority in the Shafi'i school, leading authority on the foundation of doctrine, meticulous, a devoted ascetic and one of the proponent defenders of the Ash'ari school. Wikipedia