[Machine] That the Messenger of Allah ﷺ used to perform a voluntary prayer before the obligation of the fifth of the spoils of war. When the verse was revealed "And know that anything you obtain of war booty - then indeed, for Allah is one fifth of it" [Surah Al-Anfal 41], he left the voluntary prayer that he used to perform and it became one fifth of one fifth for Allah's share and one fifth for the Prophet's share ﷺ.
أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُنَفِّلُ قَبْلَ أَنْ تَنْزِلَ فَرِيضَةُ الْخُمُسِ فِي الْمَغْنَمِ فَلَمَّا نَزَلَتِ الْآيَةُ {أَنَّمَا غَنِمْتُمْ مِنْ شَيْءٍ فَأَنَّ لِلَّهِ خُمُسَهُ} [الأنفال 41] تَرَكَ النَّفْلَ الَّذِي كَانَ يُنَفِّلُ وَصَارَ ذَلِكَ إِلَى خُمُسِ الْخُمُسِ مِنْ سَهْمِ اللهِ وَسَهْمِ النَّبِيِّ ﷺ