The Prophets
وَٱقْتَرَبَ ٱلْوَعْدُ ٱلْحَقُّ فَإِذَا هِىَ شَـٰخِصَةٌ أَبْصَـٰرُ ٱلَّذِينَ كَفَرُوا۟ يَـٰوَيْلَنَا قَدْ كُنَّا فِى غَفْلَةٍ مِّنْ هَـٰذَا بَلْ كُنَّا ظَـٰلِمِينَ
And [when] the true promise has approached; then suddenly the eyes of those who disbelieved will be staring [in horror, while they say], "O woe to us; we had been unmindful of this; rather, we were wrongdoers."
Nearby ayahs help place verse 21:97 in sequence and meaning.
وَحَرَٰمٌ عَلَىٰ قَرْيَةٍ أَهْلَكْنَـٰهَآ أَنَّهُمْ لَا يَرْجِعُونَ
And there is prohibition upon [the people of] a city which We have destroyed that they will [ever] return
حَتَّىٰٓ إِذَا فُتِحَتْ يَأْجُوجُ وَمَأْجُوجُ وَهُم مِّن كُلِّ حَدَبٍ يَنسِلُونَ
Until when [the dam of] Gog and Magog has been opened and they, from every elevation, descend
إِنَّكُمْ وَمَا تَعْبُدُونَ مِن دُونِ ٱللَّهِ حَصَبُ جَهَنَّمَ أَنتُمْ لَهَا وَٰرِدُونَ
Indeed, you [disbelievers] and what you worship other than Allah are the firewood of Hell. You will be coming to [enter] it.
لَوْ كَانَ هَـٰٓؤُلَآءِ ءَالِهَةً مَّا وَرَدُوهَا ۖ وَكُلٌّ فِيهَا خَـٰلِدُونَ
Had these [false deities] been [actual] gods, they would not have come to it, but all are eternal therein.