I heard someone ask Sahl bin Saad, "With what was the wound of the Messenger of Allah ﷺ treated?"He replied, "No one alive knows more about this than I do. Ali used to bring water in his shield, and Fatimah would wash the blood from him. Then a piece of straw mat was burned and the ashes were used to pack his wound."
حدثنا ابن أبي عمر حدثنا سفيان عن أبي حازم قال سئل
وأنا أسمع بأي شيء دووي جرح رسول الله ﷺ فقال ما بقي أحد أعلم به مني كان علي يأتي بالماء في ترسه وفاطمة تغسل عنه الدم وأحرق له حصير فحشا به جرحه
Agreed upon [by Bukhari and Muslim]. Muslim also recorded it in the Book of Jihad, the chapter on the Battle of Uhud, hadith 1790, from Muhammad bin Abu Umar, and Bukhari recorded it, hadith 243, from the hadith of Sufyan bin Uyayna, with the same wording.