Musnad Abu Ya'la al-Mawsili 150:133

'Abd al-A'la narrated to us, Sufyan ibn 'Uyaynah narrated to us, from Sumayy, from Abu Bakr ibn 'Abd al-Rahman, from 'Aisha, may Allah be pleased with her, that the Messenger of Allah (ﷺ) would be overtaken by the morning while he was in a state of major ritual impurity (junub), then he would wake up fasting.