Jami` at-Tirmidhi 2085

حَدَّثَنَا ابْنُ أَبِي عُمَرَ، قال حَدَّثَنَا سُفْيَانُ، عَنْ أَبِي حَازِمٍ، قَالَ سُئِلَ سَهْلُ بْنُ سَعْدٍ وَأَنَا أَسْمَعُ، بِأَىِّ شَيْءٍ دُووِيَ جُرْحُ رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ مَا بَقِيَ أَحَدٌ أَعْلَمُ بِهِ مِنِّي كَانَ عَلِيٌّ يَأْتِي بِالْمَاءِ فِي تُرْسِهِ وَفَاطِمَةُ تَغْسِلُ عَنْهُ الدَّمَ وَأُحْرِقَ لَهُ حَصِيرٌ فَحُشِيَ بِهِ جُرْحُهُ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ ‏.‏

Abu Hazim said:"While I was listening, Sahl bin Sa'd was asked: 'What were the wounds of the Messenger of Allah (S.A.W) treated with?' He said: 'None is alive who is more knowledgeable of it than I. 'Ali would come with water in his shield, and Fatimah would use it to wash his blood off,and a mat was burnt for him and his wounds were filled with it(its ashes)