Sahih al-Bukhari 4934
Narrated `Abdullah:
While we were with the Prophet (ﷺ) in a cave, Surat wal-Mursalat was revealed to him and he recited it, 
and I heard it directly from his mouth as soon as he recited its revelation. Suddenly a snake sprang at 
us, and the Prophet (ﷺ) said, "Kill it!" We ran to kill it but it escaped quickly. The Prophet (ﷺ) said. "It has 
escaped your evil, and you too have escaped its evil."
حَدَّثَنَا عُمَرُ بْنُ حَفْصٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا الأَعْمَشُ، حَدَّثَنِي إِبْرَاهِيمُ، عَنِ الأَسْوَدِ، عَنْ عَبْدِ اللَّهِ، قَالَ بَيْنَمَا نَحْنُ مَعَ النَّبِيِّ صلى الله عليه وسلم فِي غَارٍ إِذْ نَزَلَتْ عَلَيْهِ وَالْمُرْسَلاَتِ، فَإِنَّهُ لَيَتْلُوهَا وَإِنِّي لأَتَلَقَّاهَا مِنْ فِيهِ وَإِنَّ فَاهُ لَرَطْبٌ بِهَا، إِذْ وَثَبَتْ عَلَيْنَا حَيَّةٌ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ اقْتُلُوهَا ‏"‏‏.‏ فَابْتَدَرْنَاهَا فَذَهَبَتْ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ وُقِيَتْ شَرَّكُمْ، كَمَا وُقِيتُمْ شَرَّهَا ‏"‏‏.‏ قَالَ عُمَرُ حَفِظْتُهُ مِنْ أَبِي فِي غَارٍ بِمِنًى‏.‏