Is it permissible to sue the hotel to claim financial compensation after the death of a younger brother due to the hotel's negligence, which led to his fall into the hotel's septic tank?

Jurists stipulate, for an indirect cause to be held liable for compensation, the existence of transgression ( ta'addi), which is exceeding one's right or what is permitted by Islamic law. So, whoever directs his action towards harming others without regard for the consequences, or acts without foresight of lawful conduct, is a transgressor. An example of transgression is digging wells in a public road without the ruler's permission. However, if the digging is on the digger's own property, he is not considered a transgressor unless he intended to harm others.

Accordingly, the "digger of the sewage pit in the hotel" is not liable if he dug it in a place where it is customary to dig, and you cannot demand blood money (diyah) from him. However, if he transgressed in his digging in a place frequented by general hotel guests, then he is liable, and you can demand blood money from him at that time.