(4) باب زَكَاةِ الْفِطْرِ عَلَى الْمُسْلِمِينَ مِنَ التَّمْرِ وَالشَّعِيرِ
Sad b. Abu Sarh heard Abu Sa'id al-Khudri as saying:
We used to take out as the Zakat of Fitr one sa' of grain, or one sa' of barley or one sa' of dates, or one sa' of cheese or one sa' of raisins.
Reference: Sahih Muslim 985 a
In-book reference: Book 12, Hadith 21
USC-MSA web (English) reference(deprecated numbering scheme): Book 5, Hadith 2154