Sahih Bukhari
Sahih Bukhari Volume 002, Book 025, Hadith Number 581.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 25. Obligatory Charity Tax After Ramadhan (Zakat-ul-Fitr)
Narated By Abu Said : We used to give one Sa' of barley as Sadaqatul-Fitr (per head).