Sayyiduna Abd al-Rahman bin Samurah (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Zakah is not due on 'kus'ah', 'jabhah' and 'nukhkhah'." Abu Umar, explaining this, said: "Kus'ah" means donkeys, "jabhah" means horses, and "nukhkhah" means slaves.
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a narrator, Sulayman bin Arqam, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الزكاة / 4374