جامعة الملك فهد للبترول والمعادن
Upon receiving his PhD, Al-Daffa joined King Fahd University of Petroleum and Minerals in Dhahran, Saudi Arabia in 1972 as an Assistant Professor. Five years later, in 1977, he was promoted to Associate Professor. He also served as Chairman of the Department of Mathematical Sciences, at the same university, from 1974 to 1977, and then as Dean of the College of Sciences from 1977 to 1984. In 1980, he was promoted to Full Professor, the highest academic rank in Saudi Arabia.