Musnad Ahmad 1153:1369

Muhammad ibn Ja'far narrated to us, he said: Shu'bah narrated to us, from 'Asim, from Mu'adhah, from 'Aishah, she said: "I used to perform ghusl (ritual bath) with the Messenger of Allah, may Allah bless him and grant him peace, from a single vessel. He would hasten to me and I would hasten to him, until I would say: 'Leave some for me, leave some for me.'"