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
Amr bin Shu'ayb (may Allah have mercy on him) says: It reached me that the Prophet (peace and blessings be upon him) ordered a crier to announce: "Sadaqat al-fitr is due upon every Muslim," and he narrated the full hadith. Ata' (may Allah have mercy on him) says: Two mudds of wheat, or a sa' of dates or of barley, and in this the slave and the free person are equal.
Abd al-Razzaq likewise narrated it from Ibn Jurayj, from Amr, with a broken chain (munqati').
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7727
Amr bin Shu'ayb narrates from his father, and he from his grandfather, that the Messenger of Allah (peace and blessings be upon him) said: "Sadaqat al-fitr is due upon both the town-dweller and the desert-dweller." Abu Isa (may Allah have mercy on him) says: I asked Imam al-Bukhari (may Allah have mercy on him) about this hadith, and he said: Ibn Jurayj did not hear from Amr bin Shu'ayb.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7728