Oaths and Vows

Bukhari :: Book 8 :: Volume 78 :: Hadith 626

Narrated Abu Huraira:

Allah's Apostle said, "If Khosrau is ruined, there will be no Khosrau after him; and if Caesar is ruined, there will be no Caesar after him. By Him in Whose Hand Muhammad's soul is, surely you will spend their treasures in Allah's Cause."