Musnad Ahmad 30:150

Sufyan narrated to us, from al-Zuhri, from Sa'id, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him): "When Kisra perishes, there will be no Kisra after him, and when Caesar perishes, there will be no Caesar after him. By the One in Whose hand is the soul of Muhammad, you will surely spend their treasures in the way of Allah."