It is narrated from Sayyiduna Jabir bin Samurah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "This religion will always remain established; a group of the Muslims will keep fighting for its sake until the Hour is established."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1983