What is the "wazagh" that the Prophet commanded to kill in the Prophetic Hadith? Is it the salamander? And was it able to breathe fire?

The salamander resembles a gecko (wazagh), but it does not fall under the category of gecko that is commanded to be killed. This is because the gecko is harmful and malicious by nature, unlike the salamander, which is not harmful.

Animals that show neither harm nor benefit are disliked to be killed. It is authentically reported in Sahih Muslim that the Prophet, peace and blessings be upon him, said: "Indeed, Allah has prescribed excellence in everything. So, if you kill, then kill well." It is not an act of excellence to needlessly kill that which is not harmful.

The gecko is inherently harmful; the Prophet, peace and blessings be upon him, informed us that it used to blow on Ibrahim, peace be upon him, and for this reason, its killing was commanded. Scholars have unanimously agreed on the permissibility of killing it. Thus, a harmful animal may be killed, while a non-harmful one may not.

In summary, if harm from the salamander is established, it may be killed, not because it is a gecko, but to prevent its harm. If its harm is not established, then killing it is disliked, like other animals that cause no harm.