Abu Dawood
It is depicted as a mole on the end of his left shoulder blade, in size compared to a pigeon's egg or an apple. A passage from "Sunan Abu Dawood" (32.4071), also collected in the "Shama'il", reports how one Qurrah ibn Iyas al-Muzani on the occasion of swearing allegiance to Muhammad put his hand inside his shirt to "feel the seal".