18:7
إِنَّا جَعَلْنَا مَا عَلَى ٱلْأَرْضِ زِينَةً لَّهَا لِنَبْلُوَهُمْ أَيُّهُمْ أَحْسَنُ عَمَلًا
Indeed, We have made that which is on the earth adornment for it that We may test them [as to] which of them is best in deed.
The Cave
إِنَّا جَعَلْنَا مَا عَلَى ٱلْأَرْضِ زِينَةً لَّهَا لِنَبْلُوَهُمْ أَيُّهُمْ أَحْسَنُ عَمَلًا
Indeed, We have made that which is on the earth adornment for it that We may test them [as to] which of them is best in deed.
Nearby ayahs help place verse 18:7 in sequence and meaning.
مَّا لَهُم بِهِۦ مِنْ عِلْمٍ وَلَا لِـَٔابَآئِهِمْ ۚ كَبُرَتْ كَلِمَةً تَخْرُجُ مِنْ أَفْوَٰهِهِمْ ۚ إِن يَقُولُونَ إِلَّا كَذِبًا
They have no knowledge of it, nor had their fathers. Grave is the word that comes out of their mouths; they speak not except a lie.
فَلَعَلَّكَ بَـٰخِعٌ نَّفْسَكَ عَلَىٰٓ ءَاثَـٰرِهِمْ إِن لَّمْ يُؤْمِنُوا۟ بِهَـٰذَا ٱلْحَدِيثِ أَسَفًا
Then perhaps you would kill yourself through grief over them, [O Muhammad], if they do not believe in this message, [and] out of sorrow.
وَإِنَّا لَجَـٰعِلُونَ مَا عَلَيْهَا صَعِيدًا جُرُزًا
And indeed, We will make that which is upon it [into] a barren ground.
أَمْ حَسِبْتَ أَنَّ أَصْحَـٰبَ ٱلْكَهْفِ وَٱلرَّقِيمِ كَانُوا۟ مِنْ ءَايَـٰتِنَا عَجَبًا
Or have you thought that the companions of the cave and the inscription were, among Our signs, a wonder?