Musnad Ahmad 529:20

Mu'awiyah ibn 'Amr narrated to us, he said: Abu Ishaq—meaning al-Fazari—narrated to us, from Safwan—meaning ibn 'Amr—from Abu al-Muthanna, from 'Utbah ibn 'Abd al-Sulami—and he was one of the companions of the Prophet, may God bless him and grant him peace—who said: The Messenger of God, may God bless him and grant him peace, said: "Killing is of three types: A believing man who struggled with his self and his wealth in the way of God, until when he met the enemy, he fought them until he was killed; that is the tested martyr in the tent of God under His Throne, whom the prophets do not surpass except by the rank of prophethood. And a believing man who committed sins and errors against his own self, who struggled with his self and his wealth in the way of God, until when he met the enemy, he fought until he was killed; this cleansing wiped away his sins and his errors, for the sword is a wiper of errors, and he is entered through whichever of the gates of Paradise he wishes, for it has eight gates, and Hell has seven gates, some of them lower than others. And a hypocritical man who struggled with his self and his wealth, until when he met the enemy, he fought in the way of God until he was killed; that one is in the Fire, for the sword does not wipe away hypocrisy."