Abu Dawud Book 2, Hadith Number 1286.
Chapter : Prayer in the forenoon.
Narated By Ibn Abi Laila : No one told us that the Prophet (PBUH) had offered the prayer in the forenoon except Umm hani. She said that the Prophet (PBUH) had taken a bath in her house on the day of the Conquest of Makkah and prayed eight rak’ahs. But no one saw him afterwards praying these rak’ahs.