Sahih al-Bukhari 1507
Book 24: Obligatory Charity Tax (Zakat) · Narrated by `Abdullah bin `Umar
Arabic
حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ، حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ، قَالَ أَمَرَ النَّبِيُّ صلى الله عليه وسلم بِزَكَاةِ الْفِطْرِ، صَاعًا مِنْ تَمْرٍ، أَوْ صَاعًا مِنْ شَعِيرٍ. قَالَ عَبْدُ اللَّهِ ـ رضى الله عنه ـ فَجَعَلَ النَّاسُ عِدْلَهُ مُدَّيْنِ مِنْ حِنْطَةٍ.
English translation
Narrated `Abdullah bin `Umar:The Prophet (ﷺ) ordered (Muslims) to give one Sa' of dates or one Sa' of barley as Zakat-ul-Fitr. The people regarded two Mudds of wheat as equal to that
Reference: Sahih al-Bukhari 1507, Book of Obligatory Charity Tax (Zakat). English translation by Dr. Muhammad Muhsin Khan.