The Prophet ﷺ ordered the people to pay Zakat-ul-Fitr before going to the ʿId prayer.  

أَنَّ النَّبِيَّ ﷺ أَمَرَ بِزَكَاةِ الْفِطْرِ قَبْلَ خُرُوجِ النَّاسِ إِلَى الصَّلاَةِ  

In the lifetime of Messenger of Allah ﷺ , we used to give one Sa' of food (edible things) as Sadaqat-ul-Fitr (to the poor). Our food used to be either of barley, raisins (dried grapes), cottage cheese or dates.  

عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ ؓ قَالَ كُنَّا نُخْرِجُ فِي عَهْدِ رَسُولِ اللَّهِ ﷺ يَوْمَ الْفِطْرِ صَاعًا مِنْ طَعَامٍ وَقَالَ أَبُو سَعِيدٍ وَكَانَ طَعَامَنَا الشَّعِيرُ وَالزَّبِيبُ وَالأَقِطُ وَالتَّمْرُ