Musnad Ahmad 3551

It was narrated that 'Abdullah (رضي الله عنه) said: We were with the Prophet (ﷺ) in the cave and "By the winds (or angels or the Messengers of Allah) sent forth one after another” (al-Mursalat 77) was revealed to him. I learned it from his lips when it was fresh (had just been revealed), but I do not know with which words he ended it, “Then in what statement after this (the Qur'an) will they believe?" (v. 50) or "And when it is said to them: ‘Bow down yourself (in prayer)!’ They bow not down (offer not their prayers)” (v.48). A snake got away from us and entered a hole, and the Prophet (ﷺ) said: "You have been protected from its evil and it has been protected from your evil.”