أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ فَرَضَ رَسُولُ اللَّهِ صلى الله عليه وسلم زَكَاةَ رَمَضَانَ عَلَى كُلِّ صَغِيرٍ وَكَبِيرٍ حُرٍّ وَعَبْدٍ وَذَكَرٍ وَأُنْثَى صَاعًا مِنْ تَمْرٍ أَوْ صَاعًا مِنْ شَعِيرٍ ‏.‏

It was narrated that Ibn 'Umar said: "The Messenger of Allah enjoined the Zakah of Ramadan on everyone, young and old, free and slave, male and female, a Sa of dates or a Sa of barley." Translation Not Available

Book Ref: Sunan An Nisai Book 23 Hadith 2502
Web Ref:  Sunan An Nisai Vol 3 Book 23 Hadith 2504