Have they not seen how many generations before them We destroyed whom We had established on the earth as We have not established you? (Quran 6:6)

"Have they not seen how many generations before them We destroyed whom We had established on the earth as We have not established you? And We sent [rain from] the sky upon them in showers and made rivers flow beneath them; then We destroyed them for their sins and brought forth after them a generation of others." (Quran 6:6)

This verse is reminding people of the consequences of disobedience to Allah. It highlights how Allah has destroyed previous generations for their sins and brought forth new generations in their place. The verse also emphasizes that Allah had established those generations on earth just as he has established the current generation.

The verse mentions how Allah had sent rain from the sky upon those destroyed generations, made rivers flow beneath them, and still destroyed them for their sins. This highlights that the blessings and provisions that Allah provides to people should not be taken for granted and that those who are disobedient to Allah will be held accountable.

In this verse, Allah reminds the disbelievers of the fate of the nations that existed before them. These nations were once established on the earth with great power, but they were destroyed by Allah due to their sins and disobedience.

Allah uses the destruction of past nations as a warning to the disbelievers of the consequences of their actions. They should not be arrogant and think that they are immune to the punishment of Allah, as they are no different from the previous generations who were destroyed for their sins.

The verse also highlights the blessings that Allah had bestowed upon those nations before their destruction, such as rain from the sky and rivers flowing beneath them. This serves as a reminder that Allah is the provider of all blessings and favors, and they should be grateful for what they have been given and not take it for granted.

Furthermore, the verse also emphasizes the concept of succession on the earth, where one generation replaces another. The destruction of past nations was followed by the rise of new generations, and this cycle continues until the Day of Judgment. This serves as a warning to the disbelievers that if they do not change their ways, they too will be replaced by a generation that is more righteous and obedient to Allah.

Overall, the verse serves as a warning to the current generation to reflect on the fate of those before them and to strive to avoid the same fate by following the guidance of Allah and avoiding disobedience and sin.