The Cave
قَيِّمًا لِّيُنذِرَ بَأْسًا شَدِيدًا مِّن لَّدُنْهُ وَيُبَشِّرَ ٱلْمُؤْمِنِينَ ٱلَّذِينَ يَعْمَلُونَ ٱلصَّـٰلِحَـٰتِ أَنَّ لَهُمْ أَجْرًا حَسَنًا
[He has made it] straight, to warn of severe punishment from Him and to give good tidings to the believers who do righteous deeds that they will have a good reward
Nearby ayahs help place verse 18:2 in sequence and meaning.
ٱلْحَمْدُ لِلَّهِ ٱلَّذِىٓ أَنزَلَ عَلَىٰ عَبْدِهِ ٱلْكِتَـٰبَ وَلَمْ يَجْعَل لَّهُۥ عِوَجَا ۜ
[All] praise is [due] to Allah, who has sent down upon His Servant the Book and has not made therein any deviance.
مَّـٰكِثِينَ فِيهِ أَبَدًا
In which they will remain forever
وَيُنذِرَ ٱلَّذِينَ قَالُوا۟ ٱتَّخَذَ ٱللَّهُ وَلَدًا
And to warn those who say, "Allah has taken a son."