Hadith 5:432
Waki’ narrated to us, from al-‘Umari, from Nafi’, from Ibn ‘Umar, who said: There is no Zakat on the wealth of the Mukatab (a slave under a contract of manumission) nor the slave until they are both emancipated.
حدثنا وكيع عن العمري عن نافع عن بن عمر قال ليس في مال المكاتب ولا العبد زكاة حتى يعتقا