Narrated Abu Musa Ash'ari (may Allah be pleased with him):
A man came to the Prophet (peace and blessings of Allah be upon him) and said, "Some people fight for war booty, some for fame, and some to show their bravery. So who is the one who fights in the way of Allah (fi sabilillah)?" The Prophet (peace and blessings of Allah be upon him) replied: "Only the one who fights so that the word of Allah becomes supreme is the one who is in the way of Allah (fi sabilillah)."