Narrated 'Aisha (radiallaahu `anhaa), the wife of the Prophet (sallallaahu `alayhi wasallam):
Allah's Apostle (sallallaahu `alayhi wasallam) called the salamander a bad animal, but I did not hear him ordering it to be killed."
Wikipedia says Salamanders are typically characterized by a superficially lizard-like appearance, with slender bodies, short noses, and long tails.
Why are Salamanders bad?
In al-Saheehayn and elsewhere it is narrated via Sa’eed ibn al-Musayyib that Um Shareek told him that the Prophet (peace and blessings of Allaah be upon him) told her to kill salamanders. According to the report narrated by al-Bukhaari, he said: “It (the salamander) used to blow on Ibraaheem, peace be upon him.”
In Saheeh Muslim it is narrated via ‘Abd al-Razzaaq, Mu’ammar told us from al-Zuhri from ‘Aamir ibn Sa’d from his father that the Prophet (peace and blessings of Allaah be upon him) enjoined the killing of salamanders and called them mischief doers.
To Kill or not to Kill?
Killing salamanders is prescribed because there is a great deal of evidence to that effect.
Killing salamanders with one blow brings more reward than killing them with two blows. This was narrated in Saheeh Muslim via Khaalid ibn ‘Abd-Allaah from Suhayl ibn Abi Saalih from his father from Abu Hurayrah, that the Prophet (peace and blessings of Allaah be upon him) said:
Whoever kills a salamander with one blow will have such and such hasanah (good deeds); whoever kills it with the second blow will have such and such hasanah, less than the first; and whoever kills it with three blows will have such and such hasanah – less that the second.
Ibn Maajah (may Allaah have mercy on him) narrated in his Sunan from Saa’ibah the slave woman of al-Faakih ibn al-Mugheerah that she entered upon ‘Aa’ishah and saw a spear sitting there in her house. She said, “O Mother of the Believers, what do you do with this?” She said, “We kill these salamanders with it, because the Prophet of Allaah (peace and blessings of Allaah be upon him) told us that when Ibraaheem was thrown into the fire, there was no animal on earth but it tried to extinguish the fire, except for the salamander, which was blowing on the fire (to keep it burning). So the Messenger of Allaah (peace and blessings of Allaah be upon him) commanded that they should be killed.”
(Sunan Ibn Maajah, 3222. He said in al-Zawaa’id, the isnaad of ‘Aa’ishah’s hadeeth is saheeh, its men are thiqaat (trustworthy).)
Taken from IslamQA