Hafiz Muhammad Akbar Shah Bukhari writes: 

‘‘Mawlana [Zafar Ahmad] ‘Uthmani rendered highly valuable services in writing, preaching and issuing fatwas for approximately twenty five years in the company of Hakim al-Ummat [Mawlana Ashraf ‘Ali] Thanawi. During this time, magnificent works on Qur’anic exegesis and fiqh like Ahkam al-Qur’an and Imdad al-Ahkam came to the fore from his pen, which is clear evidence of his academic and juridical insight. Due to this, Hakim al-Ummat was so impressed by and content with his academic capabilities that he would consult only him in his personal affairs. He once said, ‘‘Mawlana Zafar Ahmad is the Imam Muhammad[1] (may Allah shower His mercy upon him) of our times and a fountainhead of religious sciences.’’ He had also instructed before his death that Mawlana Zafar Ahmad should lead his funeral prayer. Thus, it was he who was also blessed with this good fortune. His shaykh and guide, the gnostic and hadith expert of his era, Mawlana Khalil Ahmad Saharanpuri would say, ‘‘Mawlana Zafar Ahmad ‘Uthmani is the model of his uncle, Hakim al-Ummat Thanawi.’’ (Anwar al-Nazr fi Athar al-Zafar) 

Mawlana ‘Uthmani’s (may Allah sanctify his secret) academic and spiritual standing can also be gauged by the fact that his students and successors include such exemplary  scholars at whose very mention heads are bowed in reverence.  Elders such as Shaykh al-Hadith Mawlana Idris Kandhlawi, Mawlana Badr-e-‘Alam Miruthi Muhajir Madani, Mawlana ‘Abd al-Rahman Kamilpuri, Mawlana As‘ad Allah Saharanpuri, Mawlana Shams al-Haq Faridpuri, Shaykh al-Hadith Mawlana Muhammad Zakariyya Kandhlawi, Mawlana Ihtisham al-Haq Thanawi and Mawlana Sayyid ‘Abd al-Shakur Tirmidhi were his students and successors.”

Maqalat-e-‘Uthmani (Karachi: Bait al-‘Ulum, date unknown) Volume 1, p. 47

[1]           Imam Muhammad ibn al-Hasan al-Shaybani, the renowned student and companion of Imam Abu Hanifah (may Allah shower His mercy upon them)