Musnad Ahmad 1153:2134

Yahya ibn Adam narrated to us, he said: Hasan ibn Ayyash narrated to us, "Is it not mentioned from the Prophet, may Allah bless him and grant him peace, that he would wake up in the morning while in a state of janabah (major ritual impurity), then he would perform ghusl (ritual bath) and fast?" Sufyan said: Hammad narrated it to me, from Ibrahim, from al-Aswad, from Aisha.