Amr bin Sharhbayl, Abu Maysara عمرو بن شرحبيل الهمداني أبو ميسرة الكوفي · The Book of Zakah

"The Messenger of Allah enjoined Sadaqatul Fitr upon male and female, free and slave; a Sa of dates or a Sa of barley." He said: "The people considered that equivalent to half a Sa of wheat."