Musnad Abu Ya'la al-Mawsili 149:56

'Abd al-'Aziz narrated to us, Ibrahim narrated to me, from al-Zuhri, from al-Qasim ibn Muhammad, from 'Aishah: That the Messenger of Allah (ﷺ) used to perform ghusl from a vessel which was a *faraq*. She said: And I used to perform ghusl with him from the same single vessel. Ibrahim said: Al-Zuhri said: And I think the *faraq* at that time was about five *aqsat*.