Musnad Ahmad 30:2210

'Affan narrated to us, he said: 'Abd al-Rahman ibn Ibrahim narrated to us, from al-'Ala', from his father, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Rights shall certainly be rendered to their owners, until retribution is taken for the hornless sheep from the horned sheep."