Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated that al-Walid bin al-Mughirah prepared food for Quraysh. When they had eaten, he said: What do you say about this man (the Prophet, peace and blessings be upon him)? Some said: He is a sorcerer; and some said: He is not a sorcerer. Some said: He is a soothsayer; and some said: He is not a soothsayer. Some said: He is a poet; some said: He is not a poet. And some said: It is magic handed down. In the end they all agreed on the opinion that it is magic handed down. When this reached the Prophet (peace and blessings be upon him), he (peace and blessings be upon him) was grieved; he (peace and blessings be upon him) covered his head and wrapped himself in a cloak. Then Allah Almighty revealed this verse: "O you who are wrapped in a cloak! Arise and warn, and magnify your Lord, and purify your garments, and keep away from filth, and do not confer favours seeking more in return, and be patient for the sake of your Lord." [Surah al-Muddaththir: 2]
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11204