Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever sincerely asks Allah from his heart to be killed (martyrdom), then dies or is killed, will have the reward of a martyr. And whoever is wounded in the path of Allah or struck by some calamity, it will come on the Day of Resurrection with its colour like saffron and its fragrance like musk. And whoever is wounded in the path of Allah will bear the seal of the martyrs."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17341