Musnad Ahmad 27:403

Yazid narrated to us, Hajjaj ibn Artah informed us, from Wabrah, I heard Ibn Umar saying: "The Messenger of Allah, peace and blessings of Allah be upon him, commanded the killing of the wolf for the one in the state of Ihram," meaning: and the mouse, and the crow, and the kite. It was said to him: "And the snake and the scorpion?" He said: "That used to be said."