When the helmet of the Prophet ﷺ was smashed on his head and blood covered his face and one of his front teeth got broken, ʿAli brought the water in his shield and Fatima the Prophet's daughter) washed him. But when she saw that the bleeding increased more by the water, she took a mat, burnt it, and placed the ashes on the wound of the Prophet ﷺ and so the blood stopped oozing out.  

لَمَّا كُسِرَتْ بَيْضَةُ النَّبِيِّ ﷺ عَلَى رَأْسِهِ وَأُدْمِيَ وَجْهُهُ وَكُسِرَتْ رَبَاعِيَتُهُ وَكَانَ عَلِيٌّ يَخْتَلِفُ بِالْمَاءِ فِي الْمِجَنِّ وَكَانَتْ فَاطِمَةُ تَغْسِلُهُ فَلَمَّا رَأَتِ الدَّمَ يَزِيدُ عَلَى الْمَاءِ كَثْرَةً عَمَدَتْ إِلَى حَصِيرٍ فَأَحْرَقَتْهَا وَأَلْصَقَتْهَا عَلَى جُرْحِهِ فَرَقَأَ الدَّمُ  

That he heard Sahl bin Saʿd being asked about the wounds of Messenger of Allah ﷺ saying, "By Allah, I know who washed the wounds of Messenger of Allah ﷺ and who poured water (for washing them), and with what he was treated." Sahl added, "Fatima, the daughter of Messenger of Allah ﷺ used to wash the wounds, and ʿAli bin Abi Talib used to pour water from a shield. When Fatima saw that the water aggravated the bleeding, she took a piece of a mat, burnt it, and inserted its ashes into the wound so that the blood was congealed (and bleeding stopped). His canine tooth got broken on that day, and face was wounded, and his helmet was broken on his head."  

عَنْ جُرْحِ رَسُولِ اللَّهِ ﷺ فَقَالَ أَمَا وَاللَّهِ إِنِّي لأَعْرِفُ مَنْ كَانَ يَغْسِلُ جُرْحَ رَسُولِ اللَّهِ ﷺ وَمَنْ كَانَ يَسْكُبُ الْمَاءَ وَبِمَا دُووِيَ قَالَ كَانَتْ فَاطِمَةُ عَلَيْهَا السَّلاَمُ بِنْتُ رَسُولِ اللَّهِ ﷺ تَغْسِلُهُ وَعَلِيٌّ يَسْكُبُ الْمَاءَ بِالْمِجَنِّ فَلَمَّا رَأَتْ فَاطِمَةُ أَنَّ الْمَاءَ لاَ يَزِيدُ الدَّمَ إِلاَّ كَثْرَةً أَخَذَتْ قِطْعَةً مِنْ حَصِيرٍ فَأَحْرَقَتْهَا وَأَلْصَقَتْهَا فَاسْتَمْسَكَ الدَّمُ وَكُسِرَتْ رَبَاعِيَتُهُ يَوْمَئِذٍ وَجُرِحَ وَجْهُهُ وَكُسِرَتِ الْبَيْضَةُ عَلَى رَأْسِهِ  

“The Messenger of Allah ﷺ was wounded on the Day of Uhud. His molar was broken and his helmet was crushed on his head. Fatimah was washing the blood from him and ‘Ali was pouring water on him from a shield. When Fatimah realized that the water was only making the bleeding worse, she took a piece of a mat and burnt it, and when it had turned to ashes, she applied it to the wound to stop the bleeding. (Using translation from Ibn Mājah 3464)   

عَنْ جُرْحِ رَسُولِ اللهِ ﷺ يَوْمَ أُحُدٍ فَقَالَ «جُرِحَ وَجْهُهُ وَكُسِرَتْ رَبَاعِيَتُهُ وَهُشِّمَتِ الْبَيْضَةُ عَلَى رَأْسِهِ وَكَانَتْ فَاطِمَةُ بِنْتُ رَسُولِ اللهِ ﷺ تَغْسِلُ الدَّمَ وَكَانَ عَلِيٌّ ؓ يَسْكُبُ عَلَيْهَا بِالْمِجَنِّ فَلَمَّا رَأَتْ فَاطِمَةُ أَنَّ الدَّمَ لَا يَزِيدُهُ الْمَاءُ إِلَّا كَثْرَةً أَخَذَتْ قِطْعَةَ حَصِيرٍ فَأَحْرَقَتْهُ حَتَّى صَارَ رَمَادًا ثُمَّ أَلْزَقَتْهُ بِالْجُرْحِ فَاسْتَمْسَكَ الدَّمُ»