"At the time of the Messenger of Allah, we used to give a Sa' of barley, or dates, or raisins, or cottage cheese, and we continued to do so until the time of Mu'awiyah, when he said: 'I think that two Mudds of wheat from Ash-Sham are equivalent to a Sa' of barley."' (Using translation from Nasāʾī 2517)  

«كُنَّا نُخْرِجُ فِي عَهْدِ رَسُولِ اللهِ ﷺ صَاعًا مِنْ شَعِيرٍ أَوْ تَمْرٍ أَوْ زَبِيبٍ أَوْ أَقِطٍ» فَلَمْ نَزَلْ كَذَلِكَ حَتَّى كَانَ فِي عَهْدِ مُعَاوِيَةَ قَالَ مَا أَرَى مُدَّيْنِ مِنْ سَمْرَاءِ الشَّامِ إِلَّا تَعْدِلُ صَاعًا مِنْ شَعِيرٍ