Simak says that he heard Sayyiduna Jabir bin Samurah (may Allah be pleased with him) say: The Messenger of Allah (peace and blessings be upon him) said: "This religion will continue to stand, with a band of the Muslims fighting for it, until the Hour is established."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1878