Musnad Ahmad 30:1169

Abu Amir narrated to us, Zuhair—meaning Ibn Muhammad—narrated to us, from al-Ala’ ibn Abd al-Rahman, from his father, from Abu Hurairah, from the Prophet, peace and blessings of Allah be upon him, who said: "Rights shall certainly be rendered to their owners, until the hornless sheep is made to settle its score with the horned sheep on the Day of Resurrection."