One-fifth of Booty to the Cause of Allah (Khumus)
57/10. Chapter:
If somebody fights for the sake of boty
Sahih Bukhari
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا غُنْدَرٌ، حَدَّثَنَا شُعْبَةُ، عَنْ عَمْرٍو، قَالَ سَمِعْتُ أَبَا وَائِلٍ، قَالَ حَدَّثَنَا أَبُو مُوسَى الأَشْعَرِيُّ ـ رضى الله عنه ـ قَالَ قَالَ أَعْرَابِيٌّ لِلنَّبِيِّ صلى الله عليه وسلم الرَّجُلُ يُقَاتِلُ لِلْمَغْنَمِ، وَالرَّجُلُ يُقَاتِلُ لِيُذْكَرَ، وَيُقَاتِلُ لِيُرَى مَكَانُهُ، مَنْ فِي سَبِيلِ اللَّهِ فَقَالَ " مَنْ قَاتَلَ لِتَكُونَ كَلِمَةُ اللَّهِ هِيَ الْعُلْيَا فَهْوَ فِي سَبِيلِ اللَّهِ ".
Narrated Abu Musa Al-Ash`ari: A bedouin asked the Prophet, "A man may fight for the sake of booty, and another may fight so that he may be mentioned by the people, and a third may fight to show his position (i.e. bravery); which of these regarded as fighting in Allah's Cause?" The Prophet (ﷺ) said, "He who fights so that Allah's Word (i.e. Islam) should be superior, fights for Allah's Cause."
Reference : Sahih al-Bukhari 3126In-book reference : Book 57, Hadith 35USC-MSA web (English) reference : Vol. 4, Book 53, Hadith 355