Abdullah bin al-Harith bin Nawfal (may Allah be pleased with him) said: I used to ask, and I was eager that someone among the people would tell me whether the Messenger of Allah (peace and blessings be upon him) used to offer the Duha prayer. (So) Sayyidah Umm Hani bint Abi Talib (may Allah be pleased with her) told me that on the day of the Conquest of Makkah, after the day had risen, the Messenger of Allah (peace and blessings be upon him) came to me. He (peace and blessings be upon him) gave an order, and a screen was put up with a cloth. Then he (peace and blessings be upon him) performed ghusl, stood and offered eight rak'ahs. I do not know whether the Prophet's (peace and blessings be upon him) standing in them was longer, or the bowing and prostration; (rather) all of them were equal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4903