Book 25, Hadith 40

Abu Hurairah said:"I heard the Messenger of Allah (ﷺ) say: 'The parable of Mujahid (who strives in the cause of Allah) - and Allah knows best who strives in teh cause of Allah - is that of one who fasts and prays Qiyam (continually). Allah has promised Mujahid (who strives in His cause), that He will either cause him to die and admit him to paradise, or, He will bring him back safely with whatever he had earned of reward or spoils of war