Qadariyah (or Qadariya), in Islam, are adherents of the doctrine of free will. The word Qadar is derived from qadr (power or rights).
Qadariya was one of the earliest philosophical schools of thought in Islam. According to Sunni sources, the Qadariyah were censured by Muhammad himself by being compared to Zoroastrians, who likewise deny predestination. It is reported in Sunan Abu Dawood: Narrated Abdullah ibn Umar: The Prophet said, "The Qadariyyah are the Magians of this community. If they are ill, do not pay a sick visit to them, and if they die, do not attend their funerals."
The idea of Qadariyah, i.e. the Doctrine of Free-will, came from a Persian named "Sinbuya Asvāri" who was put to death by the Umayyad Caliph Abdu'l-Malik, or, according to other narratives, by Hajjaj bin Yusuf. His idea was already taught in Damascus at the end of the seventh century of our era by Ma'bad al-Juhani (died in A.D. 699), who had imbibed the doctrine from Sinbuya.