Sahih al-Bukhari 4924
صحيح البخاري#4924SahihNarrated Yahya:I asked Aba Salama, "Which Sura of the Qur'an was revealed first?" He replied, "O you, wrapped-up' (Al-Muddaththir)." I said, "I have been informed that it was, 'Read, in the Name of your Lord who created (i.e. Surat Al-Alaq)...similar to the narration related by `Ali bin Al-Mubarak, 444 above
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 65:444