It is narrated from Sayyiduna Abu Hurairah, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, said: "I will continue to fight the people until they declare that there is no deity except Allah. When they say «لا اله الا الله», they will protect their blood and wealth from me except by its due right, and their reckoning will be with Allah, the Exalted."
Hadith Referenceالسنن المأثورة / باب ما يحل من هتك حرمة مسلم / 611
Hadith Takhrijصحيح مسلم، الايمان، باب الأمر بقتال الناس حتى يقولوا ...... الخ، رقم: 20۔