A metaphysical term meaning existence, employed by philosophically–inclined thinkers such as al–Farabi (d. ca. 950), Ibn Rushd (d. 1198), al–Suhrawardi and Mulla Sadra (d. 1050/1640). According to Ibn Sina (d. 1037), God is the wajib al–wujud (the necessary existent or the one whose essence is to exist). Sufis use the term wujud in different ways. Ibn al–Arabi (d. 638/1240) is regarded as the father of the concept of wahdat al–wujud (the unity of being).