The question of the origin of Islamic mysticism has been one of the major concerns of many researchers in the field of mysticism in the recent decades. Some have maintained that Islamic mysticism is an imported product: a combination of Eastern spiritual traditions or a mixture of Manichaeism and Alexandrian philosophy. However, in order to find out the real origin of Islamic mysticism, the best way is to investigate the main questions of Islamic mysticism and to trace them in the Islamic culture and tradition. Reflecting on the personal unity of existence, the most important principle of Islamic mysticism, the author shows that Muslim mystics have been so inspired by the teachings of the Qur’an and the traditions of the Prophet and the Imams that there remains no need to look for the origin of Islamic mysticism outside the Muslim tradition.