You are reading a tafsir for the group of verses 21:76 to 21:77
وَنُوْحًا
اِذْ
نَادٰی
مِنْ
قَبْلُ
فَاسْتَجَبْنَا
لَهٗ
فَنَجَّیْنٰهُ
وَاَهْلَهٗ
مِنَ
الْكَرْبِ
الْعَظِیْمِ
۟ۚ
وَنَصَرْنٰهُ
مِنَ
الْقَوْمِ
الَّذِیْنَ
كَذَّبُوْا
بِاٰیٰتِنَا ؕ
اِنَّهُمْ
كَانُوْا
قَوْمَ
سَوْءٍ
فَاَغْرَقْنٰهُمْ
اَجْمَعِیْنَ
۟
3

The Prophet Noah performed his divine task of giving the call for the Truth among his community over an extremely long period, but except for a few individuals, nobody was reformed. At last, Noah prayed for the destruction of his community. Thereupon, such a disastrous flood set in that even the mountain tops could not provide the people with safe havens. Though this incident took place in relation to a prophet, there is solace in this for the common man also. It shows that those who make mischief in this world do not enjoy absolute freedom to do whatever they like, while one who espouses the cause of Truth is not all alone in this world. One who identifies himself with Truth, to the extent that he becomes the representative of Truth in the world, does not remain alone in this life, for God becomes his supporter; and who can overpower one who is supported by God?