One-fifth of Booty to the Cause of Allah (Khumus)
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو أُسَامَةَ، حَدَّثَنَا هِشَامٌ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ تُوُفِّيَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَمَا فِي بَيْتِي مِنْ شَىْءٍ يَأْكُلُهُ ذُو كَبِدٍ، إِلاَّ شَطْرُ شَعِيرٍ فِي رَفٍّ لِي، فَأَكَلْتُ مِنْهُ حَتَّى طَالَ عَلَىَّ، فَكِلْتُهُ فَفَنِيَ.Narrated Aisha:Allah's Messenger (ﷺ) died, and there was nothing in my house that a living being could eat, except some barley Lying on a shelf. So, I ate of it for a long period and measured it, and (after a short period) it was consumed
From Sahih al-Bukhari, whose reports the scholars accept as authentic.