The Prophets
بَلْ نَقْذِفُ بِٱلْحَقِّ عَلَى ٱلْبَـٰطِلِ فَيَدْمَغُهُۥ فَإِذَا هُوَ زَاهِقٌ ۚ وَلَكُمُ ٱلْوَيْلُ مِمَّا تَصِفُونَ
Rather, We dash the truth upon falsehood, and it destroys it, and thereupon it departs. And for you is destruction from that which you describe.
Nearby ayahs help place verse 21:18 in sequence and meaning.
وَمَا خَلَقْنَا ٱلسَّمَآءَ وَٱلْأَرْضَ وَمَا بَيْنَهُمَا لَـٰعِبِينَ
And We did not create the heaven and earth and that between them in play.
لَوْ أَرَدْنَآ أَن نَّتَّخِذَ لَهْوًا لَّٱتَّخَذْنَـٰهُ مِن لَّدُنَّآ إِن كُنَّا فَـٰعِلِينَ
Had We intended to take a diversion, We could have taken it from [what is] with Us - if [indeed] We were to do so.
وَلَهُۥ مَن فِى ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضِ ۚ وَمَنْ عِندَهُۥ لَا يَسْتَكْبِرُونَ عَنْ عِبَادَتِهِۦ وَلَا يَسْتَحْسِرُونَ
To Him belongs whoever is in the heavens and the earth. And those near Him are not prevented by arrogance from His worship, nor do they tire.
يُسَبِّحُونَ ٱلَّيْلَ وَٱلنَّهَارَ لَا يَفْتُرُونَ
They exalt [Him] night and day [and] do not slacken.