Sahih Muslim Book 54, Hadith 39
" My father said: If you see that, do not even go near it."
The Last Hour would not come before the Euphrates uncovers a mountain of gold, for which people would fight. Ninety-nine out of each one hundred would die but every man amongst them would say that perhaps he would be the one who would be saved (and thus possess this gold).
The Last Hour would not come unless the Euphrates would uncover a treasure of gold, so he who finds it should not take anything out of that.