Ishaq ibn Abi Bakr informed us; Ibn Khalil informed us; al-Labbān informed us, from al-Haddad; Abū Nuʿaym informed us: I heard Zafar ibn Ahmad. Al-Husayn ibn ʿAli narrated to me; Ahmad ibn al-Warrāq narrated to me; ʿAbd al-Rahman ibn Muhammad narrated to me.

Ibn al-Farraʾ also informed us; Ibn Qudāmah informed us; Ibn Khudayr informed us; Ibn Yusuf informed us; al-Barmakī informed us; Ibn Mardak informed us; ʿAbd al-Rahman ibn Abī Hatim narrated to us; Abū Bakr Muhammad ibn ʿAbbās al-Makki narrated to me: I heard al-Warkānī—who was the neighbor of Ahmad ibn Hanbal—say:

“On the day Ahmad ibn Hanbal died, mourning and wailing broke out among four communities: the Muslims, the Jews, the Christians, and the Magians.
On that very day, twenty thousand people embraced Islam.
In the version transmitted by Zafar, the figure is ten thousand from among the Jews, Christians, and Magians.”

This report is objectionable. It is transmitted solely by this Makkan from this Warkānī, who is unknown, and he is certainly not the well-known Warkānī, Muhammad ibn Jaʿfar, who died thirteen years before Ahmad ibn Hanbal and about whom Abū Zurʿah said: “He was a neighbor of Ahmad ibn Hanbal.”

Moreover, both customary experience and sound reason reject the possibility that thousands of people would accept Islam merely because a friend of Allah passed away, and yet the only person to relate this is an obscure narrator of no standing.
Had such a thing truly occurred, it would have become famous and reached the level of mass transmission, for many people would have been eager and motivated to report an event of that magnitude.
Indeed, if even one hundred souls had accepted Islam on account of his death, that alone would have been deemed astonishing—so what do you think? (1)