Sabians
The Sabians, sometimes also spelled Sabaeans or Sabeans, are a religious group mentioned three times in the Quran (as الصابئون al-Ṣābiʾūn, in later sources الصابئة al-Ṣābiʾa), where it is implied that they belonged to the 'People of the Book' (ahl al-kitāb). Their original identity, which seems to have been forgotten at an early date, has been called an "unsolved Quranic problem".