Musnad Ahmad 1166:14

Muhammad ibn Ja'far narrated to us, he said: Shu'bah narrated to us, from 'Amr ibn Murrah, from Ibn Abi Layla, who said: No one informed me that they saw the Prophet, peace and blessings of Allah be upon him, praying the Duha (forenoon) prayer except Umm Hani. For she narrated that the Prophet, peace and blessings of Allah be upon him, entered her house on the day of the conquest of Makkah, performed ghusl (ritual washing), and prayed eight rak'ahs. She had never seen him pray a prayer lighter than it, except that he would perfect the bowing and the prostration.