It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that once the Prophet (peace and blessings be upon him) was mentioning tribulations, when a man passed by in front. The Prophet (peace and blessings be upon him) saw him and said: "At that time, this veiled man will be martyred in a state of being oppressed." I went and saw that it was Sayyiduna Uthman (may Allah be pleased with him).
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5953