Sunan an Nasai
2501
Sahih+2

It was narrated that Ibn 'Umar said:"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

SahihAbu Ghuddah
SahihAl-Albani