Musnad Ahmad 30:2053

Mu'awiyah narrated to us, Za'idah narrated to us, he said: Sulayman al-A'mash narrated to us, from Abu Salih, from Abu Hurayrah, from the Prophet, peace and blessings of Allah be upon him, who said: "Whoever is wounded in the way of Allah—and Allah knows best who is wounded in His way—will come on the Day of Resurrection with his wound in the same state as it was the day he was wounded; its color is the color of blood, and its scent is the scent of musk."