Is it correct to kill geckos by hand? Is it proven that there is reward for killing them?

Praise be to
Allaah.

Killing geckos is prescribed
because there is a great deal of evidence to that effect. It should
be done with a tool or implement, etc. There is nothing in the reports
to specify that they should be killed by hand or to encourage killing
them by hand. I do not think that this is correct and there is no report
to this effect. That is alien to Islamic teaching and good characteristics.

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 geckos.
According to the report narrated by al-Bukhaari, he said: “It (the geckos)
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) said enjoined the killing
of geckos and called them mischief doers.

Killing geckos 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 geckos
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.” 

Shaykh Sulaymaan al-‘Alwaan. 

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 geckos 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 gecko, 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) 

And Allaah knows best.