Musnad Abu Ya'la al-Mawsili 150:204

'Abd al-A'la ibn Hammad narrated to us, Hammad ibn Salamah narrated to us, from 'Asim ibn Bahdalah, from Abu Salih, from 'Aishah, she said: The Messenger of Allah (peace and blessings of Allah be upon him) would go out for the dawn prayer while his head was dripping from sexual intercourse, not from a wet dream, and then he would fast.