Musnad Ahmad 30:3371

Yazid narrated to us, Muhammad informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurairah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "When Chosroes perishes, there will be no Chosroes after him, and when Caesar perishes, there will be no Caesar after him."