The narration in Al-Bukhari is: "The angels descend in the clouds and mention matters which has been decreed in heaven; Satan steals a hearing (listens to it stealthily) and communicates it to the soothsayers who tell along with it a hundred lies."
Commentary: Kahin (soothsayer), Munajjim (astrologer) and Arraf (foreteller) have similar characteristics but with a slight difference. All of them make predictions about the future. Kahin would overhear some jinn and disclose the secret to people which would sometimes prove true, because the jinn's source of information was Satan who sometimes stole away some information from the angels. But after the annunciation of the Prophet (PBUH) it was made impossible for jinns and satans to overhear anything in the skies. Moreover, Kahin and others of his ilk would make predictions on the basis of certain signs and circumstantial evidence which could go wrong or right. This is so even to this day. Astrological prediction is also a form of foretelling but this is often wrong. Al-'Irafah, or what is known to be as divination is also an indication of some future occurrence on the basis of certain causes and events. All the three occult arts supplement each other and also take the help of similar other things. In other words, these are all different forms of soothsaying. Geomancy also tries to tell about the invisible future. At-Tarq is the art of taking omen by striking birds with gravel on their wings or by throwing barley, etc., before them. In the latter formula, if a bird flies towards the right side, it would be a good omen; and if it goes towards the left it will be a bad one. All such things are unlawful and have been strictly forbidden by Islam. If anything predicted by these means comes by chance true, it does not furnish any justification for their validity.