Maliks Muwatta Book 9, Hadith Number 31.
Yahya related to me from Malik from Abu’n Nadr, the mawla of Umar ibn Ubaydullah, that Abu Murra, the mawla of Aqil ibn Abi Talib, told him that he had heard Umm Hani bint Abi Talib say, “I went to the Messenger of Allah, may Allah bless him and grant him peace, in the year of the conquest and found him doing ghusl while his daughter Fatima, was screening him with a garment. I said to him, ‘Peace be upon you’ and he said, ‘Who is that?’ I replied, ‘Umm Hani bint Abi Talib,’ and he said, ‘Welcome, Umm Hani!’ When he had finished his ghusl, he stood and prayed eight rakas, covering himself with one garment, and then came away. I said, ‘Messenger of Allah, the son of my mother, AIi, says that he is determined to kill so-and-so, son of Hubayra, a man I have placed under my protection.’ The Messenger of Allah, may Allah bless him and grant him peace, said, ‘We give protection to whoever you have given protection to, Umm Hani.'”
Umm Hani related that this incident happened in the morning.