Musnad Ahmad 22:14

Ya'qub narrated to us, Ibn Akhi Ibn Shihab narrated to us, from his uncle, who said: Abu Bakr ibn Abd al-Rahman ibn al-Harith ibn Hisham informed me, saying: Aisha and Umm Salama, the two wives of the Prophet, may Allah bless him and grant him peace, said: "The Messenger of Allah, may Allah bless him and grant him peace, would wake up in the morning from his family in a state of janaba (major ritual impurity), then he would perform ghusl (ritual bath) before praying the dawn prayer, and then he would fast on that day." He said: So I mentioned that to Abu Huraira, and he said: "I do not know; Al-Fadl ibn Abbas, may Allah be pleased with him, informed me of that."