In Mecca, Muhammad ibn Ismaʿil al-Bukhari narrated to us: “I heard ʿAli ibn al-Madini say:
‘Gaining deep insight into the meanings of hadith is half of knowledge, and knowing the transmitters is the other half.’

Abu al-ʿAbbas al-Sarrāj said: I heard Muhammad ibn Yunus relate that he heard ʿAli ibn al-Madini say:
‘I have omitted 100,000 hadith from my own narrations, 30,000 of them from ʿAbbād ibn Suhayb.’

It is also reported from al-Bukhari that he was asked, ‘What do you desire most?’
He answered, ‘To go to Iraq while ʿAli ibn al-Madini is still alive, so that I may sit with him.’
Abu al-ʿAbbas al-Sarrāj heard this statement directly from al-Bukhari.

Abu ʿUbayd al-Ājurri said: It was asked of Abu Dawud, ‘Is Ahmad ibn Hanbal more learned, or ʿAli?’
He replied, ‘ʿAli is more knowledgeable of the points of divergence in hadith than Ahmad.’

ʿAbd al-Muʾmin al-Nasafi reported: I asked Ṣalih ibn Muhammad, ‘Did Yahya ibn Maʿin truly memorize (the hadith)?’
He said, ‘No; he merely had familiarity with them.’
I then asked, ‘And ʿAli?’
He replied, ‘He both memorized and understood.’

Abu Dawud declared, ‘ʿAli ibn al-Madini is better than 10,000 men like al-Shadhakuni.’

ʿAbd Allah ibn Abi Ziyad al-Qaṭawani said: I heard Abu ʿUbayd say:
‘Knowledge has reached its limit with four men: Abu Bakr ibn Abi Shaybah—he has the most comprehensive collection; Ahmad ibn Hanbal—he is the most discerning in it; ʿAli ibn al-Madini—he is the most knowledgeable of it; and Yahya ibn Maʿin—he has written down the largest amount of it.’