Musnad Abu Ya'la al-Mawsili 150:350

Abu Musa narrated to us, Ibn Abi Adi narrated to us, from Sa'id, from Abu Ma'shar, from al-Nakha'i, from al-Aswad, from Aisha, who said: I used to rub it off from the garment of the Messenger of Allah, may Allah bless him and grant him peace. If I saw it, I would wash it, and if not, I would sprinkle it.