Sahih Bukhari Volume 002, Book 025, Hadith Number 579.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 25. Obligatory Charity Tax After Ramadhan (Zakat-ul-Fitr)
Narated By Ibn Umar : Allah's Apostle enjoined the payment of one Sa' of dates or one Sa' of barley as Zakat-ul-Fitr on every Muslim slave or free, male or female, young or old, and he ordered that it be paid before the people went out to offer the 'Id prayer. (One Sa' = 3 Kilograms approx.)