What is the meaning of the Hadith: "The destruction of my Ummah will be at the hands of young men from Quraysh," and does it refer to Marwan and Al-Hajjaj, and what is the stance regarding them?

The "youths" (ghilmah) from Quraysh will cause the destruction of people through their killings and the tribulations they incite. The "nation" (ummah) here refers to the Muslims of that time, comprising the Companions and their Successors. These "youths" are the rulers from Banu Umayyah, through whom tribulations occurred, and the first among them was Yazid ibn Mu'awiyah.

As for Marwan ibn al-Hakam, he was a jurist, counted among the Successors, and perhaps even a Companion. The compilers of the Sahih collections transmitted several hadiths from him, and he had a say among the people of fatwa.

As for Al-Hajjaj ibn Yusuf Al-Thaqafi, he was a governor of Iraq and was known for his leniency regarding bloodshed, but he did not leave the fold of Islam. He had good deeds, such as his care for the Qur'an and his interest in conquests. The Prophet (peace be upon him) described him as "al-Mubir" (the destroyer).

The preferred view is that no specific individual should be cursed absolutely, nor should any specific individual be loved absolutely.