The people during the lifetime of the Messenger of Allah ﷺ used to bring forth the sadaqah at the end of Ramadan when closing the fast one sa' of barley whose straw is removed, or of raisins. Abdullah said: When Umar (Allah be pleased with him) succeeded, and the wheat became abundant, Umar prescribed half a sa' of wheat instead of all these things.
كَانَ النَّاسُ يُخْرِجُونَ صَدَقَةَ الْفِطْرِ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ صَاعًا مِنْ شَعِيرٍ أَوْ تَمْرٍ أَوْ سُلْتٍ أَوْ زَبِيبٍ قَالَ قَالَ عَبْدُ اللَّهِ فَلَمَّا كَانَ عُمَرُ ؓ وَكَثُرَتِ الْحِنْطَةُ جَعَلَ عُمَرُ نِصْفَ صَاعِ حِنْطَةٍ مَكَانَ صَاعٍ مِنْ تِلْكَ الأَشْيَاءِ