Professor of Dars Kharij in Qom Seminary stated, “One of the most prominent books of the late Ayatollah Muhammad Mahdi Al-Khersan is about Ibn Abbas, entitled “موسوعةُ عبداللهِ بنِ عباس، حَبْرُ الاُمّة و تَرجُمانُ القرآن” (Encyclopedia of Abdullah ibn Abbas; the Great Scholar of Ummah and the Translation of the Quran.) This book reached 25 volumes, each volume has about 500 pages. Ayatollah Sayed Muhammad Mahdi Al-Khersan spent 25 years of his life writing this book, each volume of which took an average of one year to write.”