Musnad Ahmad 1153:1371

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Yazid al-Rishk, from Mu'adhah, who said: I asked 'Aishah about the ghusl (ritual bath) from janabah (major ritual impurity). She said: "Indeed, water does not become impure by anything. I used to perform ghusl, I and the Messenger of Allah, may Allah bless him and grant him peace, from a single vessel; he would begin and wash his hands."