Musannaf Ibn Abi Shayba 35:337

Ibn ‘Uyaynah narrated to us, from ‘Abdullah ibn Dinar, from Sulayman ibn Yasar, from ‘Arak ibn Malik, from Abu Hurayrah, attributing it to the Prophet, may Allah bless him and grant him peace, who said: There is no charity (zakat) upon a Muslim regarding his slave nor his horse.