Abu Mohammed Abdellah Ibn Mohammed Al-Azdi (Arabic: ابو محمد عبدالله بن محمد الأزدي) (ca. ? - 1033 CE), known also as Ibn Al-Thahabi, was an Arab physician, famous for writing the first known alphabetical encyclopedia of medicine.
He was born in Suhar, Oman. He moved then into Basra, then to Persia where he studied under Al-Biruni and Ibn Sina. Later he migrated to Jerusalem and finally settled in Valencia, in Al-Andalus (Islamic Spain).
He is famous for his book Kitab Al-Ma'a (The Book of Water), which is a medical encyclopedia. that lists the names of diseases, its medicine and a physiological process or a treatment. It is the first known alphabetical classification of medical terms. In this encyclopedia, Ibn Al-Thahabi not only lists the names but adds numerous original ideas about the function of the human organs. Indeed, he explains an original idea of how the vision takes place. It also contains a course for the treatment psychological symptoms. The main thesis of his medication is that cure must start from controlled food and exercise and if it persists then use specific individual medicines if it still persists then use