Sahih Muslim | Book 30 | Hadith Number 5822
Narrated by Zuhri
This hadith has been transmitted on the authority of 'Amir b. Sa'd and the words are. Allah's Messenger (may peace be upon him) said: The greatest sinner of the Muslims amongst Muslims is one who asked about a certain thing which had not been prohibited and it was prohibited because of his asking about it. This hadith has been narrated on the authority of Zuhri with the same chain of transmitters and with this addition: "A person asked about a thing from Allah's Apostle (may peace be upon him) and he indulged in hair-splitting.