Sahih Bukhari
Afflictions and the End of the World
Volume: 009 / Book Number: 088 / Hadith Number: 235
Narrated Abu Huraira:
Allah's Apostle said, "Soon the river "Euphrates" will disclose the treasure (the mountain) of gold, so whoever will be present at that time should not take anything of it." Al-A'raj narrated from Abii Huraira that the Prophet said the same but he said, "It (Euphrates) will uncover a mountain of gold (under it)."