Musnad Ahmad 1156:240

'Abd al-Rahman ibn Mahdi narrated to us, from Za'idah, from 'Ammar ibn Abi Mu'awiyah al-Bajali, from Abu Salamah, from Umm Salamah, that she used to perform ghusl (ritual bath) with the Messenger of Allah, peace and blessings of Allah be upon him, from Janabah (major ritual impurity) from a single vessel.