Tirmidhi

Hadith Commentary:

Now, this objection will not arise that sometimes a later era becomes better than an earlier era, for example, if a just ruler and follower of the Sunnah is born, such as Umar ibn Abd al-Aziz, whose era was after that of Hajjaj. He was extremely just and a follower of the Sunnah. Because the emergence of one or two such individuals does not necessitate the superiority of that era over the previous era.

Hadith Commentary:
The principle mentioned in the hadith does not apply to the era of Umar ibn Abd al-Aziz rahimahullah, which came a few years after Hajjaj ibn Yusuf, because in his time all evils had died out and people were very prosperous. However, some hadith scholars have interpreted this principle as referring to what is predominant.

According to our inclination, the superiority of the earlier era is overall in comparison to the later era. In the time of Hajjaj ibn Yusuf, there was an abundance of the noble Companions radi Allahu anhum ajma'in, and this abundance was not present in the era of Umar ibn Abd al-Aziz rahimahullah. And the era in which the Companions radi Allahu anhum ajma'in are present is superior to the era in which there is an absence of the Companions radi Allahu anhum ajma'in.

The Messenger of Allah sallallahu alayhi wa sallam said:
“My Companions radi Allahu anhum ajma'in are a guarantee of safety and security for my Ummah. When they are gone, the Ummah will face those conditions that have been promised to them.”
(Sahih Muslim, Fada’il al-Sahabah, Hadith: 6466(2531))

This is further clarified by a narration from Abdullah ibn Mas’ud radi Allahu ta'ala anhu, who said:
The later era will be worse than the earlier one until the Day of Resurrection. By this, I do not mean the abundance of wealth or the comfort of life, but the later era will be lesser in terms of knowledge and action. When the scholars are gone, all people will be equal in ignorance, and there will be no one capable of enjoining good and forbidding evil (al-amr bil-ma’ruf wa al-nahy ‘an al-munkar). At that time, their destruction will be certain.
(Fath al-Bari: 27/13)