Uqba bin 'Amir al-Juhayni · The Book of Jihad

"A man came to the Prophet (ﷺ) and said: 'What do you think of a man who fights seeking reward and fame - what will he have?' The Messenger of Allah (ﷺ) said: 'He will not have anything.' He repeated it three times, and the Prophet (ﷺ) said to him: 'He will not have anything.' Then he said: 'Allah does not accept any deed, except that which is purely for Him, and seeking His Face.'"

"O Messenger of Allah, if I am killed in the cause of Allah, will Allah forgive my sins?" The Messenger of Allah (ﷺ) said: "Yes, if you are killed in the cause of Allah, and you are patient and seek reward, and you are facing the enemy, not running way - except for debt. Jibril (peace be upon him) told me that."