From Sahih Bukhari (Hadith 243):
Narrated Abu Hazim:Sahl bin Sa`d As-Sa`idi, was asked by the people, "With what was the wound of the Prophet (ﷺ) treated?" Sahl replied, "None remains among the people living who knows that better than I. `Ali [??] used to bring water in his shield and Fatima used to wash the blood off his face. Then straw mat was burnt and the wound was filled with it
Reference: Bukhari 243