Sahih Bukhari

The Prophet (ﷺ) said, "The person who participates in (Holy battles) inAllah's cause and nothing compels him to do so except belief in Allahand His Apostles, will be recompensed by Allah either with a reward,or booty (if he survives) or will be admitted to Paradise (if he iskilled in the battle as a martyr). Had I not found it difficult for myfollowers, then I would not remain behind any sariya going for Jihadand I would have loved to be martyred in Allah's cause and then madealive, and then martyred and then made alive, and then again martyredin His cause."