Sahih al-Bukhari Hadith 4924

I asked Abu 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) Thereupon, Abu Salamah said that he asked Hadrat Jabir bin Abdullah رضی اللہ عنہما : Which chapter of the Quran was revealed first? He replied: The Mantled one. i submitted: I have been told that the chapter the clot of the Blood was the first to be revealed. He, whereupon, said: I have told you what Allah`s Apostle ﷺ told me Allah`s Apostle ﷺ said: I had retired to the Cave Hira. After completing the session, when I ascended, and reached the valley, some one called me. I, whereupon, looked forward, backward, to right and to left, and saw someone sitting on a throne in between the heaven and the earth. I came back home and asked Khadijah to wrap me up and pour the cold water on me. So, these verses were revealed to me: ''O the Mantled one. Stand up, then warn. And magnify your Lord alone.