Al-Kāfi

1. Muhammad b. al-Hasan has narrated from Ali b. Muhammad from Sahl b. Ziyad from Muhammad b. ‘Isa from Ubaydullah al-Dihqan from Durust al-Wasiti from Ibrahim b. Abdul Hamid from Abul Hasan Musa عليه السلام who has said: “Once Rasulullah صلى الله عليه وعلى آله وسلم entered the Mosque and found a group of people gathered around a man. He asked, 'Who is he?'. It was said that he was a Allamah. He then asked them, 'What is that?'. They replied that he is the most learned man about the genealogy, the chronology, and the history of the pre-Islamic days of darkness and the poetry of Arabs. He عليه السلام said, so the Prophet صلى الله عليه وعلى آله وسلم then stated that ‘such knowledge doesn't harm the one who is ignorant of it or benefit the one who knows it.' Then he صلى الله عليه وعلى آله وسلم added: ‘Knowledge consists of three kinds: A clear verse (of the Qur'an), a just obligation (i.e. a legal ruling) or an established sunnah (i.e. a hadith). Anything else is of the extra achievements.”’