Musnad Ahmad 26:102

Yahya narrated to us, from Ibn Jurayj, who said: Abu al-Zubayr informed me that Mujahid informed him that Abu Ubaydah informed him, from his father, who said: We were sitting in the Mosque of al-Khayf on the night of Arafah, before the day of Arafah, when we heard the sound of a snake. The Messenger of Allah (peace and blessings of Allah be upon him) said: "Kill it." He said: So we stood up. He said: It entered a crevice in a hole. A palm branch was brought, and he set fire to it. We took a stick and pried open some of the hole, but we did not find it. The Messenger of Allah (peace and blessings of Allah be upon him) said: "Leave it; Allah has protected it from your evil, just as He has protected you from its evil."