Surah Al-Kahf 18:87

قَالَ أَمَّا مَن ظَلَمَ فَسَوْفَ نُعَذِّبُهُۥ ثُمَّ يُرَدُّ إِلَىٰ رَبِّهِۦ فَيُعَذِّبُهُۥ عَذَابًا نُّكْرًا

He said, "As for one who wrongs, we will punish him. Then he will be returned to his Lord, and He will punish him with a terrible punishment [i.e., Hellfire].

Translation: Saheeh International

Tafsir

He said ‘As for him who does wrong by way of practising idolatry we shall chastise him We shall slay him. Then he shall be returned to his Lord and He shall chastise him with an awful chastisement read nukran or nukuran that is a severe one in the Fire.

Excerpt from Tafsir al-Jalalayn, commentary on 18:87, via Quran.com. The reader has the full commentary and 9 more tafsirs.