How sound is the Hadith: "The fourth tribulation will last twelve years, then it will subside, and the Euphrates will have receded from a mountain of gold..."? And can it be used as a proof if it is weak?

The hadith describing "the fourth fitna, blind and dark," which lasts for twelve years, is not authentic because its narrators are very weak or abandoned, such as Nu'aym ibn Hammad, Al-Junayd ibn Maymun, Ishaq ibn Abi Farwah, and Dirar ibn Amr.

What has been authentically reported is the receding of the Euphrates to uncover a mountain of gold, which is one of the signs of the Hour. People will fight over it, and ninety-nine out of every hundred will be killed. It is advised not to take anything from it due to the fitna (strife) and fighting it causes.