Mishkatul Masabih — Hadith #39774

Once he said to the people at the end of Ramadhan, give your fasting charity. Rasulullah (sallallahu alayhi wa sallam) is a date for every Muslim, free and subject, slave and captive, male and female, young and old. And barley or half of wheat of 'Ek Sa' has made Sadaqatul Fitr Farz. (Abu Dawud, Nasa'i) [1]