Sunan Abi Dawud Book 15, Hadith 61
Amr ibn Uqaysh had given usurious loans in pre-Islamic period; so he disliked to embrace Islam until he took them. He came on the day of Uhud and asked: Where are my cousins? They (the people) replied: At Uhud. He asked: Where is so-and-so? They said: At Uhud. He asked: Where is so-and-so? They said: At Uhud. He then put on his coat of mail and rode his horse; he then proceeded towards them. When the Muslims saw him, they said: Keep away, Amir. He said: I have become a believer. He fought until he was wounded. He was then taken to his family wounded. Sa'd ibn Mu'adh came to his sister: Ask him (whether he fought) out of partisanship, out of anger for them, or out of anger for Allah. He said: Out of anger of Allah and His Apostle. He then died and entered Paradise. He did not offer any prayer for Allah.
The Prophet (ﷺ) said: Our Lord Most High is pleased with a man who fights in the path of Allah, the Exalted; then his companions fled away (i.e. retreated). But he knew that it was a sin (to flee away from the battlefield), so he returned, and his blood was shed. Thereupon Allah, the Exalted, says to His angels: Look at My servant; he returned seeking what I have for him (i.e. the reward), and fearing (the punishment) I have, until his blood was shed.
Salamah bin Al Akwa’ said “On the day of the battle of the Khaibar, my brother fought desperately. But his sword fell back on him and killed him. The Companions of the Apostle of Allaah(ﷺ) talked about him and doubted it (his martyrdom) saying “A man who died with his own weapon”. The Apostle of Allaah(ﷺ) said “he died as a warrior striving in the path of Allaah. Ibn Shihab said “I asked the son of Salamah bin Al Akwa’.” He narrated to me on the authority of his father similar to that except that he said “The Apostle of Allaah(ﷺ) said “They told a lie, he died as a warrior striving in the path of Allaah. There is a double reward for him.””