Hadith: Write down; for by the One in Whose Hand my soul is, nothing comes out of it except the truth

عن عبد الله بن عمرو قال: كنتُ أكتبُ كلَّ شيء أسمعه من رسول الله صلى الله عليه وسلم أريد حفظه، فنهتني قريش، وقالوا: أتكتب كل شيء تسمعه من رسول الله صلى الله عليه وسلم ورسول الله صلى الله عليه وسلم بشر يتكلم في الغضب والرضا؟ فأمسكت عن الكتاب، فذكرت ذلك لرسول الله صلى الله عليه وسلم، فأومأ بإصبعه إلى فيه، فقال: "اكتب، فوالذي نفسي بيده، ما يخرج منه إلا حق".
[صحيح] - [رواه أبو داود]

‘Abdullāh ibn ‘Amr (may Allah be pleased with him) reported: I used to write down everything I heard from the Messenger of Allah (may Allah’s peace and blessings be upon him) in order to memorize it. The Quraysh prohibited me, saying: "Do you write down everything that you hear from the Messenger of Allah (may Allah’s peace and blessings be upon him) while he is a human being who speaks in anger and pleasure?" So, I stopped writing and talked to the Prophet (may Allah’s peace and blessings be upon him) about that. Thereupon, he pointed his finger to his mouth and said: "Write down; for by the One in Whose Hand my soul is, nothing comes out of it except the truth!"
Sahih/Authentic. - [Abu Dawood]

Explanation

‘Abdullāh ibn ‘Amr (may Allah be pleased with him) reported: I used to write down everything I heard from the Messenger of Allah (may Allah’s peace and blessings be upon him) so as to memorize it. But the Quraysh men forbade me from doing this, saying: How do you write down everything that you hear from the Messenger of Allah (may Allah’s peace and blessings be upon him), while he is a human being who he speaks in anger and pleasure and thus may err? So, I stopped writing. A person is usually influenced by what he is told. Then, I informed the Prophet (may Allah’s peace and blessings be upon him) about what they had said. Thereupon, he pointed his finger to his mouth and said: Write down; for by the One in Whose Hand my soul is, nothing comes out of it except the truth! So, he (may Allah’s peace and blessings be upon him) made clear that everything he said is true, whether he said it in a state of anger or pleasure. Indeed, he was infallible with regard to what he conveyed from his Lord. Someone may cite this Hadīth narrated by Muslim (No. 2363), which relates that the Messenger of Allah (may Allah’s peace and blessings be upon him) passed by people who had been busy in grafting the trees. He said: "If you were not to do it, it might be good for you." So they abandoned this practice and there was a decline in the yield. Then, he passed by them and said: "What has gone wrong with your trees?" They said: "You said such and such." Thereupon, he said: "You have better knowledge about your worldly affairs." Replying to this, we say: There are two things in this Hadīth: First: It is related to this specific incident and not a general rule. Second: It does not give a Shar‘i ruling. Anything that does not fall under these two categories falls under the general rule mentioned above.