Narrated from Umm al-Mu'mineen Aisha Siddiqa (may Allah be pleased with her) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "There are five harmful animals that may be killed even in the state of Ihram: the crow, the kite, the scorpion, the mouse, and the biting dog."

Narrated Abdullah bin Mas'ud (may Allah be pleased with him): While we were with the Messenger of Allah (peace and blessings of Allah be upon him) in a cave at Mina, Surah Al-Mursalat was revealed to him. He began to recite it, and I started memorizing it from him as he recited. While he was still reciting it, suddenly a snake leapt towards us. The Prophet (peace and blessings of Allah be upon him) said: "Kill it." So we rushed towards it, but it escaped. The Prophet (peace and blessings of Allah be upon him) then said: "It has been saved from your harm just as you have been saved from its harm."

Umm al-Mu'mineen Aisha Siddiqa (may Allah be pleased with her) narrates from the Noble Prophet (peace and blessings of Allah be upon him) that the Messenger of Allah (peace and blessings of Allah be upon him) said about the lizard: "It is harmful." But I did not hear him (peace and blessings of Allah be upon him) giving the order to kill it. (However, it should be killed.)