No Sadaqa is payable on the grains and dates till it (comes to the Weight) of five wasqs, or less than five heads of camels, or less than five uqiyas (of silver). (Using translation from Muslim 979f)  

أَنَّ النَّبِيَّ ﷺ قَالَ «لَيْسَ فِي حَبٍّ وَلَا فِي تَمْرٍ صَدَقَةٌ حَتَّى يَبْلُغَ خَمْسَةَ أَوْسُقٍ وَلَا فِيمَا دُونَ خَمْسِ ذَوْدٍ وَلَا فِيمَا دُونَ خَمْسِ أَوَاقٍ صَدَقَةٌ»