Musnad Ahmad 1153:960

Al-Hakam ibn Marwan narrated to us, he said: Isra'il narrated to us, from Jabir, from 'Amir, from Masruq, 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, while we were both in a state of janabah (major ritual impurity). However, water does not become junub (ritually impure)."