Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) ordered a crier to announce in the valley of Makkah: "Sadaqat al-fitr is obligatory upon every Muslim, whether young or old, male or female, free or slave, town-dweller or desert-dweller: a sa' of barley or a sa' of dates."
Yahya bin Abbad alone narrated this hadith from Ibn Jurayj in this way; others narrated it from Ibn Jurayj, from Ata', as Ata's own statement regarding the two mudds, and from Ibn Jurayj, from Amr bin Shu'ayb, attributed to the Prophet (peace and blessings be upon him) in the rest of its wording.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7726