We read in the Shiite book, Ijtihad o Taqleed
“During the time of Sheikh Sudooq there were Five big books of Ahadees. The 5th one was ‘Madina-tul-Ilm’ which consisted of Twelve Volumes, and it was the biggest book of Ilmul-Hadees, which disappeared…………Imam Sadiq (s.a.) narrated Four Hundred Books of Ahadees, named ‘Usool-e-Arbamia’, all of them are not with us anymore.”
(Ijtihad o Taqleed P69)
Akhbari scholar Alsyyed Abu Mohammad Abrar al-Hasnain Fatimi al-Naqvi writes regarding it in his book, The Two Paths
It is truth that total 401 books of Ahadees disappeared and were lost at once. How it happened? Who did it? Why it was done? Whose benefit was in it? Do you find any historical incident that any Sunni group or non-Muslim attacker attacked all of the Shia Educational Institutions at once in different cities, and confiscated and destroyed only and only Ahadees Books but left behind the books on Ilmul Usool & Fiqh untouched?
If even now it is not clear in Usooli mind, that this house was burnt with its own candle, then that time is not really far that Zulfiqar-e-Haidari will make the mouths open to tell who made the Traditions of Masomeen (s.a.) disappear.
At another place, he says:
Then Shias were left with only Five books on Ahadees, the biggest book among them was “Madina-tul-Ilm” comprising of 12 Volumes, which also disappeared Or a Jinn flew away with it! So we were left with only 4 books i.e. Kutub-e-Arba’a:
1- Usool al-Kafi, 2- Tehzeeb-ul-Ahkaam, 3- al-Istabsaar, 4- Mun La Yahzurul Faqih.