Sahih Muslim Book 1, Hadith Number 34.

Chapter : Command for fighting against the people so long as they do not profess that there is no god but Allah and Muhammad is His Messenger.

It Is narrated on the authority of Abu Malik: I heard the Messenger of Allah (may peace be upon him) say: He who professed that there is no god but Allah and made a denial of everything which the people worship beside Allah, his property and blood became inviolable, an their affairs rest with Allah.