It is narrated from Mujahid and Mughira bin Hakim, may Allah have mercy on them, they say: We heard Sayyiduna Abu Huraira, may Allah be pleased with him, saying: "No one knew the hadiths of the Messenger of Allah, peace and blessings be upon him, more than me, except Sayyiduna Abdullah bin Amr bin Al-As, may Allah be pleased with them both. The reason for this is that he used to write them down with his hand and memorize them by heart, whereas I used to memorize them by heart but did not write them down." He had sought permission from the Messenger of Allah, peace and blessings be upon him, to write, and he, peace and blessings be upon him, granted him permission.