Musnad Ahmad 1153:2228

Yunus narrated to us, Umar ibn Ibrahim al-Yashkuri narrated to us, he said: I heard my mother narrating that her mother went to the House (the Kaaba) as a pilgrim, and the House on that day had two doors. She said: When I finished my circumambulation, I entered upon Aisha. She said: I said, "O Mother of the Believers, some of your sons have sent you greetings of peace, and the people have spoken much regarding Uthman, so what do you say about him?" She said: "May Allah curse those who curse him, may Allah curse those who curse him,"—I do not think she said it except three times—"I have seen the Messenger of Allah (peace and blessings of Allah be upon him) while he was leaning his thigh against Uthman, and I was wiping the sweat from the forehead of the Messenger of Allah (peace and blessings of Allah be upon him) while the revelation was descending upon him. And he married his two daughters to him, one after the other, and he would say, 'Write, Uthman.'" She said: "Allah would not place a servant of His Prophet in that position unless he was a servant noble to Him."