كتاب الجهاد والسير
32  
The Book of Jihad and Expeditions
(13)
Chapter: The killer is entitled to the belongings of the one who is killed
(13)
باب اسْتِحْقَاقِ الْقَاتِلِ سَلَبَ الْقَتِيلِ ‏‏
Sahih Muslim 1753 b

It has been narrated on the authority of Auf b. Malik al-Ashja'i who said:

I joined the expedition that marched under Zaid b. Haritha to Muta, and I received reinformcement from the Yemen. (After this introduction), the narrator narrated the tradition that had gone before except that in his version Auf was reported to have said (to Khalid): Khalid, didn't you know that the Messenger of Allah (way peace be upon him) had decided In favour of giving the booty (sized from an enemy) to one who killed him? He (Khalid) said: Yes. but I thought it was too much.
وَحَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، حَدَّثَنَا صَفْوَانُ بْنُ عَمْرٍو، عَنْ عَبْدِ، الرَّحْمَنِ بْنِ جُبَيْرِ بْنِ نُفَيْرٍ عَنْ أَبِيهِ، عَنْ عَوْفِ بْنِ مَالِكٍ الأَشْجَعِيِّ، قَالَ خَرَجْتُ مَعَ مَنْ خَرَجَ مَعَ زَيْدِ بْنِ حَارِثَةَ فِي غَزْوَةِ مُؤْتَةَ وَرَافَقَنِي مَدَدِيٌّ مِنَ الْيَمَنِ ‏.‏ وَسَاقَ الْحَدِيثَ عَنِ النَّبِيِّ صلى الله عليه وسلم ‏.‏ بِنَحْوِهِ غَيْرَ أَنَّهُ قَالَ فِي الْحَدِيثِ قَالَ عَوْفٌ فَقُلْتُ يَا خَالِدُ أَمَا عَلِمْتَ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَضَى بِالسَّلَبِ لِلْقَاتِلِ قَالَ بَلَى وَلَكِنِّي اسْتَكْثَرْتُهُ ‏.‏
Reference : Sahih Muslim 1753b
In-book reference : Book 32, Hadith 52
USC-MSA web (English) reference : Book 19, Hadith 4343
  (deprecated numbering scheme)