Sahih Muslim Book 5, Hadith Number 2153.
Chapter : Taking out of Sadaqat-ul-Fitr before observing Fitr prayer.
Ibn Umar reported that the Messenger of Allah (may peace be upon him) prescribed Zakat-ul-Fitr of Ramadan one sa’ of dates or one sa’ of barley for every individual among the Muslims (whether) free man or slave, male or female, young or old.