Sahih al-Bukhari 3120
Sahih al-Bukhari · Book 57: One-fifth of Booty to the Cause of Allah (Khumus) · The statement of the Prophet ﷺ: "Booty has been made legal for you Muslims."
Narrated Abu Huraira:
حَدَّثَنَا أَبُو الْيَمَانِ ، أَخْبَرَنَا شُعَيْبٌ ، حَدَّثَنَا أَبُو الزِّنَادِ ، عَنِ الأَعْرَجِ ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا هَلَكَ كِسْرَى فَلاَ كِسْرَى بَعْدَهُ، وَإِذَا هَلَكَ قَيْصَرُ فَلاَ قَيْصَرَ بَعْدَهُ، وَالَّذِي نَفْسِي بِيَدِهِ، لَتُنْفِقُنَّ كُنُوزَهُمَا فِي سَبِيلِ اللَّهِ " .
Allah's Messenger (ﷺ) said, "When Khosrau is ruined, there will be no Khosrau after him; and when Caesar is ruined, there will be no Caesar after him. By Him in Whose Hands my life is, you will spend their treasures in Allah's Cause."