Hadith 8:2192
Abu Bakr narrated to us, he said: Salam narrated to us, from Mukharriq ibn Abd al-Rahman, from Tariq ibn Shihab, who said: I passed by some snakes while I was in the state of ihram, so I killed them with a stick that was with me. When I came to Umar, I asked him about killing them. He said: "Kill them, for they are an enemy."
حدثنا أبو بكر قال حدثنا سلام عن مخارق بن عبد الرحمن عن طارق بن شهاب قال مررت بحيات وأنا محرم فقتلتهن بعصا كانت معي فلما أتيت عمر سألته عن قتلهن فقال أقتلهن فإنهن عدو