It is narrated from Sayyidah Aishah (may Allah be pleased with her) that when they intended to wash the Messenger of Allah (peace and blessings be upon him), the people disagreed. Some said: Shall we remove the clothes of the Messenger of Allah (peace and blessings be upon him) as we remove the clothes of our dead, or shall we wash him with his clothes on him? Then Allah Almighty sent drowsiness upon them, until there was not one of them but that his chin rested on his chest from sleep. Then a speaker from a corner of the house said (and they did not know who it was): "Wash the Messenger of Allah (peace and blessings be upon him) with his clothes on his blessed body." So they washed him while his (peace and blessings be upon him) shirt was on his (peace and blessings be upon him) body, pouring water over it and rubbing him from over it. Aishah (may Allah be pleased with her) says: "By Allah, had I known beforehand about my affair what I came to know afterwards, no one would have washed the Messenger of Allah (peace and blessings be upon him) except his (peace and blessings be upon him) wives."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6621
Abbad bin Abdullah bin al-Zubayr (may Allah have mercy on him) says: I heard Sayyidah Aishah (may Allah be pleased with her) saying, and he narrated the whole hadith, except that he said: They washed him (peace and blessings be upon him) while a shirt was on him (peace and blessings be upon him); they poured water over the shirt and rubbed the body with the shirt itself, without their hands.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6622
Ibn Buraydah narrates from his father (Sayyiduna Buraydah, may Allah be pleased with him) that when the matter of washing the Messenger of Allah (peace and blessings be upon him) arose, a caller called out to them from inside: "Do not remove the shirt of the Messenger of Allah (peace and blessings be upon him)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6623