One-fifth of Booty to the Cause of Allah (Khumus)
حَدَّثَنَا إِسْحَاقُ، سَمِعَ جَرِيرًا، عَنْ عَبْدِ الْمَلِكِ، عَنْ جَابِرِ بْنِ سَمُرَةَ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا هَلَكَ كِسْرَى فَلاَ كِسْرَى بَعْدَهُ، وَإِذَا هَلَكَ قَيْصَرُ فَلاَ قَيْصَرَ بَعْدَهُ، وَالَّذِي نَفْسِي بِيَدِهِ، لَتُنْفَقَنَّ كُنُوزُهُمَا فِي سَبِيلِ اللَّهِ ".Narrated Jabir bin Samura:Allah's Messenger (ﷺ) said, "When Khosrau is ruined, there will be no Khosrau after him; and when Caesar is ruined, their will be no Caesar after him. By Him in Whose Hands my life is, you will spend their treasures in Allah's Cause
From Sahih al-Bukhari, whose reports the scholars accept as authentic.