Yahya related to me from Malik from Zayd ibn Aslam from lyad ibnAbdullah ibn Sad ibn Abi Sarh al-Amiri that he had heard Abu Said al-Khudri say, "We used to pay the zakat al-fitr with a sa of wheat, or asa of barley, or a sa of dates, or a sa of dried sour milk, or a sa ofraisins, using the sa of the Prophet, may Allah bless him and granthim peace . "
USC-MSA web (English) reference: Book 17, Hadith 54
Arabic reference: Book 17, Hadith 630