Sahih Al Bukhari – Book of One-fifth Of Booty To The Cause Of Allah (Khumus)

Volumn 004, Book 053, Hadith Number 329.
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Narated By 'Aisha RA: Allah's Apostle PBUH 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.