Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) said: "On the day the face of the Messenger of Allah (peace and blessings be upon him) was wounded, Sayyidah Fatimah (may Allah be pleased with her) would burn a mat and treat his (peace and blessings be upon him) wound with its ashes, sticking it onto the wound."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5734