It is narrated from Sayyiduna Sahl bin Sa'd al-Sa'idi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Islam began as something strange and will soon return to being strange, so glad tidings are for the strangers." The Companions said: O Messenger of Allah, who are the strangers? He (peace and blessings be upon him) said: "Those who set things right when the people have become corrupt."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5846