Musnad Ahmad 1301:21

Abu Sa’id narrated to us, he said: Abu Ya’qub, meaning Ishaq ibn ‘Uthman al-Kilabi, narrated to us, he said: I heard Khalid ibn Durayk narrating from Abu al-Darda’, raising the hadith to the Prophet, may Allah bless him and grant him peace, he said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Allah will not combine in the interior of a man the dust of the path of Allah and the smoke of Hell. Whoever’s feet become dusty in the path of Allah, Allah will forbid the rest of his body to the Fire. Whoever fasts one day in the path of Allah, Allah will distance the Fire from him by the distance of a thousand years for a swift rider. Whoever receives a wound in the path of Allah, it will be sealed for him with the seal of the martyrs; he will have a light on the Day of Resurrection, its color like the color of saffron, and its scent like the scent of musk. The first and the last will recognize him by it; they will say: 'So-and-so has the stamp of the martyrs.' Whoever fights in the path of Allah for the duration of the milking of a she-camel, Paradise becomes mandatory for him."