Sheikhul Hadith, Hadhrat Moulana Zakariyya Rahmatullahi ‘Alaihi wrote: “Humaidi Rahmatullahi ‘Alaihi is a Muhaddith who has combined Saheeh Bukhaari and Saheeh Muslim in one compilation. It is said that he wrote throughout the night. When it was hot, he would write while sitting in a tub of water.
Imaam Tabrani Rahmatullahi ‘Alaihi is a reputated Muhaddith and author of numerous books. Somebody enquired: “How could you write so many books, Shaikh?”
He replied: “I have been on my mat of thirty years.”
Abul Abbas Shirazi Rahmatullahi ‘Alaihi says:
“I have learnt 300 000 Ahaadith from Tabrani”
Imaam Abu Hanifah Rahmatullahi ‘Alaihi laboured very hard in going deep into those Ahaadith which (seem to) contradict some others. Koofah was the centre of Islamic learning in those days. He had collected Hadith from all Muhadditheen of that place. Whenever a Muhaddith from outside came to Koofah, he sent his students to him to ascertain if he knew any such Hadith that was not known to him. The Imaam had established a circle where scholars of Hadith, FIqah and Philology gathered together. They had discussions on regulations about Islamic practices. Sometimes the discussions continued for one month before a point was agreed upon, and written in the book of regulations for the people of his school of thought.
Imaam Tirmidhi Rahmatullahi ‘Alaihi is known to one and all. He was unique in his capacity for memorising and retainingbo Ahaadith. His memory was marvellous. Some Muhadditheen once tested his memory. They recited before him forty one Ahaadith. Imaam Tirmidhi Rahmatullahi ‘Alaihi immediately repeated all of them. He himself writes:
“On my way to Makkah, I copied two parts from the collections of Hadith by a Shaikh. I happened to come across that Shaikh personally. I said to him, “I have copied two parts of your collections. I wish to compare those Ahaadith by listening to them directly from you. The Shaikh agreed. While going to his place I, by mistake, took a blank book instead of the note book in which I had copied the Ahaadith. The Shaikh started reciting the Ahaadith, while I held the blank in my hand. When he noticed it, he was very angry with me. I explained to him how that had happened, and said, “Shaikh, your time is not wasted. I remember everything that you have said.’ He did not believe me and asked me to repeat all that he had recited. I repeated all the Ahaadith. He though I had memorised them before I came. I said, “You may recite some other Ahaadith.” He recited forty Ahaadith. I repeated all of them without any error.”
Fadhaail-e-A’maal pg 157, Zeal for Knowledge