Who was the first physician to document accurate descriptions of measles and smallpox?

The first physician to document accurate descriptions of measles and smallpox was Muhammad ibn Zakariya al-Razi, also known as Rhazes, a Persian physician who lived in the 9th and 10th centuries. He was one of the most influential physicians of the Islamic Golden Age and made significant contributions to the field of medicine. He was the first to describe measles and smallpox as distinct diseases, providing detailed descriptions of their symptoms and complications. He also developed a method of inoculation for smallpox, which involved exposing individuals to a mild form of the disease to induce immunity.