It is narrated from Sayyiduna Murrah al-Bahzi (may Allah be pleased with him); he said: The Messenger of Allah (peace and blessings be upon him) said: "A trial (fitnah) will arise upon the earth, spreading like the horns of cattle." Just then a man passed by with his face covered, and he (peace and blessings be upon him) said: "This man and his companions will be upon guidance on that day." And it was seen that he was Sayyiduna Uthman bin Affan (may Allah be pleased with him).
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17881