Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) commanded the payment of sadaqat al-fitr, "one sa' of barley or dates on behalf of every young and old, free and slave," and the people considered it equal to two mudds of wheat.
Abdullah bin al-Walid narrates it through Ubaydullah alone: "It is on behalf of every young and old, free and slave."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7677