Musnad Ahmad 1153:2287

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, who said: Yahya ibn 'Abbad ibn 'Abdullah ibn al-Zubayr narrated to me, from his father, from 'Aishah, the wife of the Prophet, may Allah bless him and grant him peace, who said: When they intended to wash the Messenger of Allah, may Allah bless him and grant him peace, they differed regarding it. They said: "By Allah, we do not know what we should do. Should we strip the Messenger of Allah, may Allah bless him and grant him peace, as we strip our dead, or should we wash him while his clothes are upon him?" She said: When they differed, Allah cast drowsiness upon them, until, by Allah, there was not a man among the people whose chin was not upon his chest, asleep. She said: Then someone spoke to them from a corner of the house, they did not know who he was, saying: "Wash the Prophet, may Allah bless him and grant him peace, while his clothes are upon him." She said: So they rose to him, and they washed the Messenger of Allah, may Allah bless him and grant him peace, while he was in his shirt, pouring water and lotus leaves over him, and the men rubbed him with the shirt. She used to say: "If I had known then what I know now, no one would have washed the Messenger of Allah, may Allah bless him and grant him peace, except his wives."