What is the ruling on dealing with a man who claims spirituality and knowledge of what is beneath the earth to extract a doubtful treasure (rikaz), knowing that he deals with jinn and shows no signs of shirk, and what is the danger of believing him, and is it permissible to insist on dealing with him if there is no other way to extract the treasure?

It is impermissible to excavate buried treasures using Jinn, whether they be Muslim or disbeliever. The claim of knowing what is beneath the earth and seeing it is an assertion of knowledge of the unseen and of secrets, which falls under forbidden soothsaying. It is not permissible to go to such people or ask them questions, even if one does not believe them. For whoever goes to a diviner and asks him about something, his prayer will not be accepted for forty nights. Believing them is more severe and graver, for whoever goes to a soothsayer or a diviner and believes what he says, has disbelieved in what was revealed to Muhammad, peace be upon him. Protecting a place and expelling devils is possible through legitimate Sharia (definition)-compliant methods.