Sahih al-Bukhari 1512

Arabic

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ عُبَيْدِ اللَّهِ، قَالَ حَدَّثَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنه ـ قَالَ فَرَضَ رَسُولُ اللَّهِ صلى الله عليه وسلم صَدَقَةَ الْفِطْرِ صَاعًا مِنْ شَعِيرٍ، أَوْ صَاعًا مِنْ تَمْرٍ عَلَى الصَّغِيرِ وَالْكَبِيرِ وَالْحُرِّ وَالْمَمْلُوكِ‏.‏

English translation

Narrated Ibn `Umar:Allah's Messenger (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

Reference: Sahih al-Bukhari 1512, Book of Obligatory Charity Tax (Zakat). English translation by Dr. Muhammad Muhsin Khan.