Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the Prophet (peace and blessings be upon him) "prescribed sadaqat al-fitr as a sa' of dates or barley on behalf of every free person and slave, male and female, young and old, among the Muslims, and the Prophet (peace and blessings be upon him) ordered that sadaqat al-fitr be paid before going out to the Eid prayer ground."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7688