Messenger of Allah ﷺ has made Sadaqat-ul-Fitr obligatory, (and it was), either one Sa' of barley or one Sa' of dates (and its payment was obligatory) on young and old people, and on free men as well as on slaves. (Using translation from Bukhārī 1512)
فَرَضَ رَسُولُ اللهِ ﷺ صَدَقَةَ الْفِطْرِ عَلَى الصَّغِيرِ وَالْكَبِيرِ وَالْحُرِّ وَالْمَمْلُوكِ صَاعًا مِنْ تَمْرٍ أَوْ شَعِيرٍ