Musnad Abu Ya'la al-Mawsili 150:10

Ishaq ibn Abi Isra'il narrated to us, Muhammad ibn Bakr narrated to us, Ibn Abi 'Arubah narrated to us, from Qatadah, from Mu'adhah, from 'Aishah, who said: "Command your husbands to wash the traces of excrement and urine, for I am shy of them, and the Messenger of Allah (peace and blessings of Allah be upon him) used to do that."