The Scholars say that knowing the condition of Men is Half of Knowledge. This statement points to the importance of the art of the science of men or commonly known as 'Ilm ar-Rijaal. This book Rawnaq al-Alfaadh Mu'jim al-Hufaadh is an encyclopedia of Hadith narrators that is written by Jamaal ad-Deen Abul Mahaasin Yusuf bin Shaheen Ibn Ameer Sibtu Ibn Hajar al-Qahiree al-Hanafi thumma ash-Shafi'i. Printed on fine yellow paper in four volumes.