Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "Whoever goes to a sorcerer or a soothsayer and believes him has disbelieved in what was revealed to Muhammad (peace and blessings be upon him)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب القسامة / 16496