Hadith: He is not one of us who seeks omens or has omens interpreted for him, or who practices soothsaying or has it done for him, or who practices sorcery or has it done for him. And whoever goes to a soothsayer and believes in what he says has disbelieved in what was revealed to Muhammad (may Allah's peace and blessings be upon him)

عن عمران بن حصين رضي الله عنه وابن عباس رضي الله عنهما مرفوعاً: «ليس منا من تَطَيَّر أو تُطُيِّر له، أو تَكَهَّن أو تُكِهِّن له، أو سحَر أو سُحِر له؛ ومن أتى كاهنا فصدَّقه بما يقول؛ فقد كفر بما أنزل على محمد صلى الله عليه وسلم ».
[صحيح] - [رواه البزار عن عمران بن حصين -رضي الله عنهما-. ورواه الطبراني في الأوسط عن ابن عباس -رضي الله عنهما]

‘Imrān ibn Husayn and Ibn ‘Abbās (may Allah be pleased with both of them) reported that the Prophet (may Allah's peace and blessings be upon him) said: "He is not one of us who seeks omens or has omens interpreted for him, or who practices soothsaying or has it done for him, or who practices sorcery or has it done for him. And whoever goes to a soothsayer and believes in what he says has disbelieved in what was revealed to Muhammad (may Allah's peace and blessings be upon him)."
Sahih/Authentic. - [Al-Bazzaar]

Explanation

The Prophet (may Allah's peace and blessings be upon him) says that whoever believes in bad omens or practices soothsaying or black magic, or has any of these things done to him, is not one of his followers who adhere to the Islamic Shariah. These practices involve the claim of having knowledge of the unseen that only Allah has, and they spoil people's minds and beliefs. Whoever believes the person who does these evil practices has in fact disbelieved in the divine revelation that has come to abolish such ignorant practices and protect the minds from them. Among the practices that fall under this category are "palm reading" and "cup reading", or linking one's happiness or misery to his zodiac sign and the like. Imām Al-Baghawi and Imām Ibn Taymiyyah explained that fortuneteller, soothsayer, astrologer, and geomancer are all share a common concept of claiming knowledge of the unseen. Anyone who claims knowledge of the unseen is either a soothsayer or does some sort of soothsaying. This is because soothsayer is someone who says what will happen in the future based on the information he receives from the devils who eavesdrop on the heavens.