The Book on Government (Kitab Al-Imara)
Muslim :: Book 20 : Hadith 4686
It has been narrated (through yet another chain of transmitters) on the same authority, i. e. Abu Musa, who said: We, came to the Messenger of Allah (may peace be upon him) and said: Messenger of Allah, one of us hho fights to display his valour... (followed by the same words as we have in the previous tradition).