Sahih Bukhari
Sahih Bukhari Volume 002, Book 025, Hadith Number 588.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 25. Obligatory Charity Tax After Ramadhan (Zakat-ul-Fitr)
Narated By Ibn 'Umar : Allah's Apostle has made Sadaqatul-Fitr obligatory, (and it was), either one Sa' of barley or one Sa' of dates (and its payment was obligatory) on young and old people, and on free men as well as on slaves.