Musnad Ahmad 1273:10

Hajjaj and Shu'ayb ibn Harb narrated to us, they said: Layth narrated to us, he said: Yazid ibn Abi Habib narrated to me, from Suwayd ibn Qays, from Mu'awiyah ibn Hudayj, from Mu'awiyah ibn Abi Sufyan, that he asked his sister, Umm Habibah, the wife of the Prophet (peace and blessings of Allah be upon him): "Did the Messenger of Allah (peace and blessings of Allah be upon him) pray in the single garment in which he had intercourse with her?" She said: "Yes, if there was no harm [impurity] on it."