A Treatise on the Muhammedan Law contains two works, Al-Nahr al-fa’id fi ‘ilm al-fara’id (The overflowing river of the science of inheritance and patrimony), and Al-Idah fi huquq al-nisa’ wa ahkam al-nikah (The rights of women, and the laws of matrimony). Written in English and Arabic, it is a textbook on Islamic law for judges and attorneys in the courts of Aden. The strategically important territory of Aden in the Arabian Peninsula became a British possession in 1839. The population was ethnically mixed, with Muslim Arabs predominating. British administrative policy aimed at allowing each community to adjudicate disputes according to its own laws. Thus, judges, who were British, needed guidance on complex issues of inheritance and marriage according to Islamic jurisprudence. The Treatise was written to fill this need. The author, Qadi (judge) ‘Abd al-Qadir ibn Muhammad al-Naqshbandi, also known as al-Makki or al-Makkawi, presented the topic according to the Hanafi and Shafiʻi schools of law, satisfying the requirements of Muslims of Arab and Indian origin. Little is known of the author. From his names, it can be surmised that he or his forebears were from Mecca and that he was an adherent of the Naqshbandi Sufi fraternity. He is termed “judge,” but his role in the court system was as teacher and advisor. He writes in the introduction that he, his son, and brother taught Arabic to British judges and provided them background on Islamic personal status law, as when he argues the case for polygamy. His Treatise may have found acceptance in Aden’s courts for its clear presentation, but it probably took second place to Minhāj al-tālibīn (The method) by al-Nawawi (1233‒77), a manual of Shafiʻi inheritance law. The first part of this work was published in 1886. In the 1899 edition shown here, the first text is revised and expanded, and the second half of the book, “The Rights of Women, and the Laws of Matrimony,” is published for the first time. There is also an Egyptian edition, and a German translation by explorer Leo Hirsch, published in Leipzig in 1891 together with the original Arabic text. The German translation is also presented in the World Digital Library.