Musnad Abu Ya'la al-Mawsili 210:14

Muhammad ibn Abi Bakr al-Muqaddami narrated to us, Abu Ma'shar narrated to us, Ibrahim ibn 'Umar narrated to us, he said: My father narrated to me, from 'Abdullah ibn 'Umar, from Hafsah, the wife of the Prophet (peace and blessings of Allah be upon him), that she was sitting, and 'Aishah was with the Messenger of Allah (peace and blessings of Allah be upon him). The Messenger of Allah (peace and blessings of Allah be upon him) said: "I wish some of my companions were with me so we could talk." 'Aishah said: "Shall I send for Abu Bakr to talk with you?" He said: "No." Hafsah said: "Shall I send for 'Umar to talk with you?" He said: "No, but send for 'Uthman." So 'Uthman came and entered, and they (the two women) stood up and let down the curtain. The Messenger of Allah (peace and blessings of Allah be upon him) said to 'Uthman: "You will be killed as a martyr, so be patient—may Allah grant you patience—and do not take off a shirt that Allah, the Mighty and Majestic, has clothed you with for twelve years and six months, until you meet Allah while He is pleased with you." 'Uthman said: "If the Prophet (peace and blessings of Allah be upon him) prays for patience for me." So he said: "O Allah, grant him patience." Then 'Uthman went out. When he turned away, the Messenger of Allah (peace and blessings of Allah be upon him) said: "May Allah grant you patience, for you will be martyred and you will die while you are fasting, and you will break your fast with me."