Musnad Abu Ya'la al-Mawsili 252:27

Abu Ibrahim al-Turjumani, Isma'il ibn Ibrahim, narrated to us, saying: 'Abd al-'Aziz—meaning Ibn Abi Hazim—narrated to us, from his father, from Sahl ibn Sa'd, that a man asked him about the wounding of the face of the Messenger of Allah, may Allah bless him and grant him peace. He said: "The face of the Messenger of Allah, may Allah bless him and grant him peace, was wounded, his incisor tooth was broken, and the helmet was shattered upon his head. Fatima, daughter of Muhammad, may Allah bless him and grant him peace, was washing the blood, and 'Ali was pouring water onto it with a shield. When Fatima saw that the water only increased the blood in its flow, she took a piece of a reed mat and burned it until it became ash, then she applied it to the wound, and the blood stopped."