Maliks Muwatta Book 6, Hadith Number 8.
Section : Watching the Night in Prayer.
Yahya related to me from Malik from Hisham ibn Urwa from his father that Dhakwan Abu Amr (a slave belonging to A’isha, the wife of the Prophet, may Allah bless him and grant him peace, who was freed by her after her death) used to stand in prayer and recite for her in Ramadan.