Musnad Ahmad 1153:1360

Muhammad ibn Ja‘far narrated to us, he said: Sa‘id and Bahz narrated to us, they said: Hammam narrated to us, from Qatadah, from Mu‘adhah, from ‘Aishah, that she said: "Command your husbands to wash away from themselves the trace 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 it." Bahz said: "Command your husbands."