Sahih al-Bukhari · Hadith 3097

One-fifth of Booty to the Cause of Allah (Khumus)

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