Killing the lizard.
Umm Shurayk relates that Allah's Messenger peace be upon him ordered the wazagh to be killed, and he said: "It had blown on (the fire) of Abraham (peace be upon him)." [Sahh al-Bukhr (3359)]
The animal in question is a type of house gecko known in Arabic by the name wazagh. It is a common household pest in the Middle East that lives on the walls and in the crevices of people's homes.
The instruction to kill the Lizard (wazagh is for the same reason ' it is a pest that poses harm to people. If a lizard comes in contact with the skin, it can sometimes induce serious irritation. For this reason, it is also known to Arabs as smm abras (literally, "the leprosy venom").
It is not killed because of its blowing on the fire kindled for Abraham (peace be upon him). When Prophet Muhammad (peace be upon him) informed us that the lizard blew upon the fire of Abraham (peace be upon him) to help fan the flames, he was merely depicting the distastefulness of the animal and the extent of its harmfulness. He was merely characterizing this species as an unpleasant one.