Musnad Ahmad 25:473

Uthman ibn Muhammad narrated to us, Jarir narrated to us, from Layth, from Tawus, from Ibn Abbas, from the Prophet, peace and blessings of Allah be upon him, who said: "Five, all of which are vicious (fasiqah), may be killed by the one in ihram, and they may be killed within the Sacred Precinct (Haram): the mouse, the scorpion, the snake, the biting dog, and the crow."