This paper, entitled "Science of Difficult Words of the Qur'an", begins with a discourse on the status of this science among other Qur'anic sciences. Then, it gives a definition of this science from among the definitions of the Qur'an researchers and goes on to delve into the history of the science of "Qarīb al-Qur'an" (Difficult Words of the Qur'an) up to the time of the companions of the Holy Prophet (S.A.W.) and points out the endeavors made by such erudite scholars as Abān b. Thaqlab, Abū ‘Ubayda Mu‘ammar b. Muthannā Taymī, Abū Zakariyā Yaḥyā b. Ziyād Farrā’, Abū Bakr Sajistānī, and Rāqib Isfahānī. Another discourse which has been dealt with in this paper is the introduction of the systematized works of the above scholars in the field of "Qarīb al-Qur'an", their style, and the features of their works. In conclusion, the book by Abū al-Qāsim Ḥusayn b. Muḥammad Rāqib Isfahānī, "Al-Mufradāt fī Alfāẓ al-Qur'ān", which is a turning point in the development of the science of "Qarīb al-Qur'an", is touched upon.
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