Musnad Abu Ya'la al-Mawsili 152:105

Abu Khaythama narrated to us, Jarir narrated to us, from al-A'mash, from Abu Razin, from Zirr, who said: Ibn Mas'ud said: "Surat al-Mursalat was revealed to the Messenger of Allah (peace and blessings of Allah be upon him) while we were in a cave. He recited it to me, and I am reciting it close to how he recited it to me. I do not know with which of its endings he ended it: 'And when it is said to them, "Bow," they do not bow,' or 'Then in what message after it will they believe?'"