Safiyyah bint Abi Ubayd narrates from one of the wives of the Prophet (peace and blessings be upon him): "Whoever goes to a fortune-teller (one who claims knowledge of the unseen), Allah does not accept his prayer for forty days."
This report is mawquf (that is, it is the Companion's own statement, not narrated directly from the Prophet (peace and blessings be upon him)).
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19695