The purpose of this article is to provide a concise and brief introduction to the classical Islamic law of waqf. This study is based on the Fiqh literature of four Sunni schools of thought. The primary focus is on the Ḥanafī Fiqh, however, representative texts of the other schools have also been taken into account. There are three major findings in this article. First, the law contained in Fiqh texts is incomplete because it does not encompass ʿurf (custom) and qānūn (imperial decrees). Custom is recognised in these texts in support of Fiqh, but qānūn is totally missing despite references to the power of rulers regarding certain provisions of waqf law. Second, the legal theory is inconsistent, as the majority of jurists hold that the ownership of a founder terminates with the creation of a waqf. However, not only the founder and his legal heirs maintain a limited proprietary interest in waqf property; the waqf also dissolves with the apostasy of its founder. Third, family awqāf (pl. of waqf) come into direct conflict with the law of inheritance and the law of gifts. However, the testamentary waqf and waqf during terminal illness are subservient to inheritance law, and jurists have tried to harmonise waqf law with inheritance law whenever an opportunity arose.