Musnad Ahmad 1153:2385

I found in my father’s book: ‘Amir ibn Salih narrated to us, he said: Hisham ibn ‘Urwah narrated to me, from his father, from ‘Aishah, that she informed him that she and the Messenger of Allah, peace and blessings of Allah be upon him, used to perform ghusl (ritual bathing) from a single vessel, both of them scooping from it.