Narrated ‘Abdullah:
While we were in the company of the Prophet in a cave at Mina, when Surat-wal-Mursalat were revealed 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 said (ordered us): “Kill it.” We ran to kill it but it escaped quickly. The Prophet said, “It has escaped your evil and you too have escaped its evil.”
Sahih Bukhari, Volume 3, Book 29, Number 56