From Sahih Muslim (Hadith 766):
This hadith is narrated by Sa'id b. Abu Hind with the same chain of transmitters and said:His (the Holy Prophet's) daughter Fatimah provided him privacy with the help of his cloth, and when he had taken a bath he took it up and wrapped it around him and then stood and offered eight rak'ahs of the forenoon prayer
Reference: Muslim 766