Sahih Muslim Book 005, Hadith Number 2136.

Chapter : No Zakat is due from a Muslim or his slave or his horse.

'Umara reported: I heard Abd Sa'id al-Khudri as saying that he had heard Allah's Messenger (may peace be upon him) make (this) observation with a gesture of his five fingers, and then he narrated the Hadith as transmitted by 'Uyaina (Hadith 2134).