Musnad Ahmad 29:5

Yunus narrated to us, Hammad—meaning Ibn Salamah—narrated to us, from ‘Asim, from Abu Rimthah, who said: I came to the Messenger of Allah (ﷺ), and with him were people from Rabi‘ah disputing over a case of intentional homicide. I heard him say: "Your mother and your father, and your sister and your brother, then your nearest and then your nearest." Then he said: He looked, and then said: "Who is this with you, O Abu Rimthah?" I said: My son. He said: "As for him, he does not commit a crime against you, nor do you commit a crime against him." He said: I looked, and there was on the cartilage of his shoulder something like the dung of a camel or the egg of a pigeon. I said: Shall I not treat it for you, O Messenger of Allah, for we are a family that practices medicine? He said: "The One who placed it will treat it."