Musnad Ahmed: Hadith 3979

We were with the Messenger of Allah (ﷺ) in a cave and (the soorah) "By the winds (or angels or the Messengers of Allah) sent forth one after another” (al-Mursalat 77:1] was revealed; we learned it from his lips. Then a snake came out of its hole, and we rushed to kill it but it got away from us and entered its hole. Then he said: "It was protected from your evil as you were protected from its evil.”