Sahih al-Bukhari 3125
Sahih al-Bukhari · Book 57: One-fifth of Booty to the Cause of Allah (Khumus) · The war booty is for those who witness the battles
Narrated Aslam:
حَدَّثَنَا صَدَقَةُ ، أَخْبَرَنَا عَبْدُ الرَّحْمَنِ ، عَنْ مَالِكٍ ، عَنْ زَيْدِ بْنِ أَسْلَمَ ، عَنْ أَبِيهِ ، قَالَ قَالَ عُمَرُ ـ رضى الله عنه لَوْلاَ آخِرُ الْمُسْلِمِينَ مَا فَتَحْتُ قَرْيَةً إِلاَّ قَسَمْتُهَا بَيْنَ أَهْلِهَا كَمَا قَسَمَ النَّبِيُّ صلى الله عليه وسلم خَيْبَرَ.
`Umar said, "Were it not for those Muslims who have not come to existence yet, I would have distributed (the land of) every town I conquer among the fighters as the Prophet (ﷺ) distributed the land of Khaibar."