Whoever goes to a soothsayer and asks him about something and believes him, his prayer will not be accepted for forty nights

The Prophet (may Allah's peace and blessings be upon him) warns us against going to soothsayers - a general term also applying to fortune tellers, astrologers, geomancers, and others who use certain things as means for knowing the unseen - and says that if a person merely asks a soothsayer about anything of the unseen, Allah will deny him the reward for his prayers for forty days, as a punishment for this great sin and misdeed.