possessing strong memory and all the scholars who possess great knowledge of hadith must agree upon the narrators' ability to learn and memorize, along with their reporting techniques, complete isnad without any missing narrators, consecutive narrators in the chain must meet each other. Bukhari began organizing his book in the Masjid al-Haram in Mecca, before moving to the Al-Masjid an-Nabawi in Medina. Bukhari completed writing the book in Bukhara around 846 (232 AH), before showing it to his teachers for examination and verification. Ibn Hajar al-Asqalani quoted Abu Jaʿfar al-‘Uqaili as saying, "After Bukhari had written the Sahih, he showed it to Ali ibn al-Madini, Ahmad ibn Hanbal, Yahya ibn Ma'in as well as others. They examined it and testified to its authenticity with the exception of four hadith." Ibn Hajar then concluded with al-'Uqaili's saying, "And those four are as Bukhari said, they are authentic." Bukhari spent the last twenty-four years of his life visiting other cities and scholars, making minor revisions to his book and teaching the hadith he had collected. In every city that Bukhari visited, thousands of people would gather to listen to him recite traditions. Transmission Each version of the Sahih is named by its narrator. Ibn Hajar al-Asqalani in his book Nukat asserts the number of narrations is the same in each version. There are many books that noted differences between the different versions, the best known being Fath al-Bari. The version transmitted by Muhammad ibn Yusuf al-Firabri (d. 932), a trusted student of Bukhari, is the most famous version of the Sahih al-Bukhari today. All modern printed version are derived from this version. Al-Khatib al-Baghdadi quoted al-Firabri in History of Baghdad: "About seventy thousand people heard Sahih Bukhari with me." al-Firabri is not the only transmitter of Sahih al-Bukhari. Many others narrated the book, including Ibrahim ibn Ma'qal (d. 907), Hammad ibn Shakir (d. 923), Mansur Burduzi (d. 931) and Husain Mahamili (d. 941). Derived works The orientalist Manjana said in Cambridge in 1936 that the oldest manuscript he had come across up to that point was written in 984 (370 AH), according to the narration of al-Mirwazi from al-Firabri. The oldest full manuscript is a version on the narration of Abu Dharr al-Heravi (d. 1043) written in Maghrebi script, present in the Süleymaniye Library in Istanbul is from 1155 (550 AH). Commentaries The number of detailed commentaries on the Sahih are numbered