Sahih Bukhari
Obligatory Charity Tax After Ramadaan (Zakat ul Fitr)
Volume: 002 / Book Number: 025 / Hadith Number: 580
Narrated Ibn 'Umar:
Allah's Apostle made it incumbent on all the slave or free Muslims, male or female, to pay one Sa' of dates or barley as Zakat-ul-Fitr.