Musnad Ahmad 27:428

Yazid narrated to us, Muhammad informed us, from Nafi' and 'Ubayd Allah ibn 'Abd Allah ibn 'Umar, who both narrated to him, from Ibn 'Umar, who said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "There is no blame upon anyone for killing five [creatures]: the crow, the mouse, the kite, the scorpion, and the vicious dog."