Question
My brother was lost 45 days ago, and we searched for him everywhere, but we have not found him yet. Without our knowledge, one of our relatives went to a soothsayer and the soothsayer guided him to the place where we might find our brother. Would we be sinning if we went to that place, or would the sin be our relative's who went to the soothsayer alone?
Fatwa
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and messenger.
Going to soothsayers or diviners and believing what they say is an act of faithlessness. That is because the Prophet said that whoever went to a soothsayer or a diviner and believed in what he said had no faith in what was sent to Muhammad . [Ahmad, As-Suyooti classified it as Hasan (good) Hadeeth] Thus, it is not permissible to go to soothsayers or to believe in them. Acting according to what he said means you believe in him. Only the person who does this will be sinning.
At the same time, you have to advise your relative and explain to him how dangerous it is to seek the help of soothsayers and diviners, and that most of what they say is lies and delusion. Explain to him that all matters are in the Hands of Allah The Almighty. That means that Allah The Almighty knows the condition of your brother and if you are destined to find him, this will definitely happen. Nothing happens except what Allah The Almighty has decreed and ordained in His prior Knowledge.
Remind him of the story of Yoosuf (Joseph), may Allah exalt his mention, and how Allah The Almighty reunited him and his father and brothers after many years. On the other hand, you may continue pursuing the Shar‘i (legislated by Islamic law) means and supplicate Allah The Almighty much and seek His Help. This can solve this problem, Allah willing.
And Allah knows best.