Abu Dawud
Zakat
Book Number: 003 / Hadith Number: 1615
Narated By Tha'labah ibn Su'ayr : The Apostle of Allah (pbuh) said: One sa' of wheat is to be taken from every two, young or old, freeman or slave, male or female. Those of you who are rich will be purified by Allah, and those of you who are poor will have more than they gave returned by Him to them. Sulayman added in his version: "rich or poor"