The Messenger of Allah ﷺ mentioned a coming tribulation, and a man passed by. The Prophet ﷺ said, "This veiled man will be killed unjustly on that day."I looked, and it was Uthman bin Affan.
ذكر رسول الله ﷺ فتنة فمر رجل، فقال: يقتل فيها هذا المقنع يومئذ مظلوما، قال: فنظرت فإذا هو عثمان بن عفان.
Tirmidhi (3708) and Ahmad (5953) both narrated it from the hadith of Aswad bin Amir, from Sinan bin Harun (who is Burjumi), from Kulayb bin Waail, from Ibn Umar, and he mentioned it. Its chain is hasan because of Sinan bin Harun, for there is disagreement about him, but his hadith is hasan when he does not contradict others and does not bring anything objectionable. Ibn Hajar graded its chain sahih in Fath al-Bari (7/38).