Muhammad bin Salmah محمد بن سلمة بن عبد الله الباهلي · The Chapters Regarding Zakat

Ibn Shihab said: “Salim read to me a letter that the Messenger of Allah had written concerning Sadaqat, before Allah caused him to pass away, in which it was said: 'For five camels one sheep; for ten, two sheep; for twenty, four sheep. For twenty five, a Bint Makhad(a one year old she-camel), up to thirty-five; if there is no Bint Makhad, then a Bin Labun ( a two-year-old male camel). If there are more than thirty-five even one, then…

that the Messenger of Allah enjoined Sadaqatul-Fitr, one Sa of dates, one Sa of barley, or one Sa of Sult (a kind of barley without skin on it, resembling wheat).