Sahih Bukhari Volume 002, Book 025, Hadith Number 584.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 25. Obligatory Charity Tax After Ramadhan (Zakat-ul-Fitr)
Narated By Abu Sa'id Al-Khudri : In the life-time of the Prophet we used to give one Sa' of food or one Sa' of dates or one Sa' of barley or one Sa' of Raisins (dried grapes) as Sadaqat-ul-Fitr. And when Muawiya became the Caliph and the wheat was (available in abundance) he said, "I think (observe) that one Mudd (of wheat) equals two Mudds (of any of the above mentioned things).