Surah Al-Kahf 18:21

وَكَذَٰلِكَ أَعْثَرْنَا عَلَيْهِمْ لِيَعْلَمُوٓا۟ أَنَّ وَعْدَ ٱللَّهِ حَقٌّ وَأَنَّ ٱلسَّاعَةَ لَا رَيْبَ فِيهَآ إِذْ يَتَنَـٰزَعُونَ بَيْنَهُمْ أَمْرَهُمْ ۖ فَقَالُوا۟ ٱبْنُوا۟ عَلَيْهِم بُنْيَـٰنًا ۖ رَّبُّهُمْ أَعْلَمُ بِهِمْ ۚ قَالَ ٱلَّذِينَ غَلَبُوا۟ عَلَىٰٓ أَمْرِهِمْ لَنَتَّخِذَنَّ عَلَيْهِم مَّسْجِدًا

And similarly, We caused them to be found that they [who found them] would know that the promise of Allāh is truth and that of the Hour there is no doubt. [That was] when they disputed among themselves about their affair and [then] said, "Construct over them a structure. Their Lord is most knowing about them." Said those who prevailed in the matter, "We will surely take [for ourselves] over them a masjid."

Translation: Saheeh International

Tafsir

And so just as We aroused them it was that We disclosed them to their people and the believers that they that is their people might know that God’s promise of resurrection is true by virtue of the fact that One Who has the power to make them sleep for such a long period of time or sustain them in that state without …

Excerpt from Tafsir al-Jalalayn, commentary on 18:21, via Quran.com. The reader has the full commentary and 9 more tafsirs.