Fadala bin Ubayd reported,

I heard the Messenger of Allah ﷺ say, "The true fighter is the one who fights against his own soul for Allah," or he said, "in the cause of Allah."

قال وسمعت رسول الله ﷺ يقول المجاهد من جاهد نفسه لله أو قال في الله عز وجل