Is it permissible to kill four-legged reptiles (lizards) inside or outside the mosque, and what other reptiles must be killed?

If geckos are harmless insects, then killing them is disliked (makruh). It is not obligatory to kill reptiles, but rather it is recommended (mandub) to kill those that are harmful and have no benefit, such as geckos (wazagh) and snakes, except for house snakes, which should be warned three times before being killed. Animals are of four types: those that are beneficial without harm, and thus it is not permissible to kill them; those that are harmful without benefit, and thus it is recommended to kill them; those that have both benefit and harm, and thus it is neither recommended nor disliked to kill them; and those that have neither benefit nor harm, and thus it is neither forbidden nor recommended. It is not permissible to kill geckos and similar creatures whose dead bodies are impure (najis) and have flowing blood in the mosque if that leads to its defilement, because their dead bodies are impure.