Sunan an-Nasa'i, Volume 3, Book 23, Hadith 2507 (DarusSalam) ⓘ
It was narrated that Ibn 'Umar said: "The Messenger of Allah enjoined Sadaqatul Fitr upon young and old, male and female, free and slave; a Sa' of dates or a Sa' of barley,"
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا عِيسَى، قَالَ حَدَّثَنَا عُبَيْدُ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ فَرَضَ رَسُولُ اللَّهِ صلى الله عليه وسلم صَدَقَةَ الْفِطْرِ عَلَى الصَّغِيرِ وَالْكَبِيرِ وَالذَّكَرِ وَالأُنْثَى وَالْحُرِّ وَالْعَبْدِ صَاعًا مِنْ تَمْرٍ أَوْ صَاعًا مِنْ شَعِيرٍ .
also referenced under: Hadith 2505 (Reference) & Book 23, Hadith 0 (In-Book)