Sahih Bukhari | Volume 4 | Hadith Number 815

Narrated by Abu Huraira
Allah's Apostle said, "When Khosrau perishes, there will be no (more) Khosrau after him, and when Caesar perishes, there will be no more Caesar after him. By Him in Whose Hands Muhammad's life is, you will spend the treasures of both of them in Allah's Cause."