Hadrat Mufti Mahmud Hasan Gangohi (may Allah shower His mercy upon him) relates: 

”Hadrat Shaykh al-Islam Mawlana Husayn Ahmad Madani once attended a jalsa at a Madrasah in Azamgarh. I also attended.  I informed Hadrat , ‘I am [currently] studying your letters (maktubat). He replied, ‘How are my letters worth studying, [when] some were written in prison, others whilst travelling by train.’ I asked, ‘Then whose letters should I read?’ He replied, ‘Read the letters of Mujaddid Alf-e-Thani (Shaykh Ahmad Sirhindi)! Read the letters of Hadrat [Mawlana Rashid Ahmad] Gangohi.” [1] 

 [1] Those who wish to read the maktubat of Imam Rabbani Mawlana Rashid Ahmad Gangohi (may Allah sanctify his secret) may refer to Makatib-e-Rashidiyyah published by Idara Islamiat (Lahore, Pakistan) (translator)

Malfuzat Faqih al-Ummat (Karachi: Dar al-Huda, September 2005 ed.),  Vol 3, Page 209