Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "There is no zakah on a man for his horse and his slave, except sadaqat al-fitr." Ibn Abi Maryam stated: There is no zakah on a Muslim for his slave and his horse except sadaqat al-fitr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7674