Sahih Bukhari Volume 002, Book 025, Hadith Number 583.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 25. Obligatory Charity Tax After Ramadhan (Zakat-ul-Fitr)
Narated By 'Abdullah bin 'Umar : The Prophet ordered (Muslims) to give one Sa' of dates or one Sa' of barley as Zakat-ul-Fitr. The people rewarded two Mudds of wheat as equal to that.