Shu'bah bin al-Hajjaj شعبة بن الحجاج · The Book on Al-Witr

"No one informed that they saw Allah's Messenger praying Ad-Duha except Umm Hani. She narrated that Allah's Messenger entered her house on the Day of the Conquest of Makkah. He performed Ghusl and performed eight voluntary Rak'ah such that she had not ever seen him pray any Salat lighter than them, but that he completed the bowing and prostrations."