Musnad Ahmad 1153:1362

Muhammad ibn Ja'far narrated to us, he said: Sa'id and 'Abd al-Wahhab narrated to us, from Sa'id, from Qatadah, from Mu'adhah al-'Adawiyyah, from 'Aishah, that she said: "I used to perform ghusl, I and the Messenger of Allah, may Allah bless him and grant him peace, from a single vessel."