Sahih Ibn Khuzaymah

Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) made obligatory the giving of one sa’ of dates or one sa’ of barley as Sadaqat al-Fitr on behalf of every free person, slave, man, and woman. Then people considered half a sa’ of wheat equivalent to one sa’ (of dates or barley). And whenever Sayyiduna Ibn Umar (may Allah be pleased with them both) would give Sadaqat al-Fitr, he would give it from dates, except for one year when dates were scarce, so he gave it from barley. Ayub says that I asked, “When would Sayyiduna Ibn Umar (may Allah be pleased with them both) give one sa’ of Sadaqat al-Fitr?” Imam Nafi’ replied, “When the collector appointed to receive Sadaqat al-Fitr would sit to collect it.” I asked, “When would the collector sit to collect it?” He replied, “One or two days before Eid al-Fitr.”