Musnad Ahmad 26:853

'Ali ibn Bahr narrated to us, 'Isa ibn Yunus narrated to us, from al-A'mash, from Abu Razin, from Ibn Mas'ud, who said: "I was with the Messenger of Allah, peace and blessings of Allah be upon him, in the cave, when [the Surah] 'By the winds sent forth' (al-Mursalat) was revealed to him. I recited it close to how he recited it to me, except that I do not know with which of the two verses it ended."