It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with him), he says: Whatever I heard from the Messenger of Allah, I used to write it down with the intention of memorizing it. But the Quraysh forbade me from this and said: You write down whatever you hear from the Messenger of Allah (peace and blessings be upon him), even though the Messenger of Allah (peace and blessings be upon him) is a human being; sometimes he speaks in a state of anger and sometimes in a normal state. So I stopped writing down his words, but when I mentioned this to the Messenger of Allah (peace and blessings be upon him), he said: You should write, by the One in whose hand is my soul, nothing comes out of my mouth except the truth.