It has been narrated on the authority of Abdullah b. 'Umar that the Messenger of Allah ﷺ used to give (from the spoils of war) to small troops seat on expeditions something more than the due share of each fighter in a large force. And Khums (one-fifth of the total spoils) was to be reserved (for Allah and His Apostle) in all cases.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَدْ كَانَ يُنَفِّلُ بَعْضَ مَنْ يَبْعَثُ مِنَ السَّرَايَا لأَنْفُسِهِمْ خَاصَّةً سِوَى قَسْمِ عَامَّةِ الْجَيْشِ وَالْخُمْسُ فِي ذَلِكَ وَاجِبٌ كُلِّهِ  

The Messenger of Allah ﷺ used to give to some of the detachments he sent out (something extra) for themselves in particular apart from the division made to the whole army. The fifth is necessary in all that.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَدْ كَانَ يُنَفِّلُ بَعْضَ مَنْ يَبْعَثُ مِنَ السَّرَايَا لأَنْفُسِهِمْ خَاصَّةً النَّفْلَ سِوَى قَسْمِ عَامَّةِ الْجَيْشِ وَالْخُمُسُ فِي ذَلِكَ وَاجِبٌ كُلُّهُ  

The Messenger of Allah ﷺ used to give to some of the detachments he sent out (something extra) for themselves in particular apart from the division made to the whole army. The fifth is necessary in all that. (Using translation from Abū Dāʾūd 2746)   

أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُنَفِّلُ بَعْضَ مَنْ يَبْعَثُ مِنَ السَّرَايَا لِأَنْفُسِهِمْ خَاصَّةً سِوَى قَسْمِ عَامَّةِ الْجَيْشِوَالْخُمُسُ فِي ذَلِكَ وَاجِبٌ لِلَّهِ تَعَالَى  

The Messenger of Allah ﷺ used to give to some of the detachments he sent out (something extra) for themselves in particular apart from the division made to the whole army. The fifth is necessary in all that. (Using translation from Abū Dāʾūd 2746)  

أَنَّ رَسُولَ اللَّهِ ﷺ قَدْ كَانَ «يُنَفِّلُ بَعْضَ مَنْ يَبْعَثُ مِنَ السَّرَايَا لِأَنْفُسِهِمْ خَاصَّةَ النَّفَلِ سِوَى قَسْمِ عَامَّةِ الْجَيْشِ وَالْخُمُسُ فِي ذَلِكَ وَاجِبٌ كُلُّهُ»