Sahih Muslim
The Book on Government (Kitab Al-Imara)
Book Number: 020 / Hadith Number: 4718
It has been narrated on the authority of Jabir b. 'Abdullah who said: I heard the Messenger of Allah (may peace be upon him) say: A group of people from my Umma will continue to fight In defence of truth and remain triumphant until the Day of judgment.