Here he remained until his retirement in 1990, when he held the post of director of the Department of Oriental Studies.
He became a Professor Emeritus of "Arab and Islamic Studies" in the University of Pennsylvania in Philadelphia.
He published an Arabic edition of the work by IBN AQIL, Al-Wāḍiḥ fi Usul al-fiqh (The Obvious in the Principles of Jurisprudence), in three volumes, published in Stuttgart, Germany by Steiner Verlag and reprinted by Klaus Schwarz.
He published an Arabic edition of a portion of IBN AQIL's huge work, Kitab al-Funun, 2 vols., printed in Beirut 1970-71.
[2] In 1977, he served as the President of the Middle East Studies Association of North America, now based in Tucson, Arizona, United States.