Musnad Ahmad 168:4

Muhammad narrated to us, Shu'bah narrated to us, he said: From 'Abd Rabbih, from Nafi', from 'Abdullah ibn 'Umar, that he used to order the killing of all snakes. Abu Lubabah sought his permission to enter the mosque through a small door (khawkha) belonging to them, and he saw them killing a snake. Abu Lubabah said to them: "Has it not reached you that the Messenger of Allah, peace and blessings of Allah be upon him, forbade the killing of those that inhabit houses and dwellings, and ordered the killing of the one with two stripes (dhu al-tufyatayn) and the tailless one (al-abtar)?"