Surah Al-Kahf 18:12

ثُمَّ بَعَثْنَـٰهُمْ لِنَعْلَمَ أَىُّ ٱلْحِزْبَيْنِ أَحْصَىٰ لِمَا لَبِثُوٓا۟ أَمَدًا

Then We awakened them that We might show which of the two factions was most precise in calculating what [extent] they had remained in time.

Translation: Saheeh International

Tafsir

Then We aroused them We awakened them that We might know a knowledge of direct vision which of the two parties the two groups in disagreement over the length of their stay in the cave was better in calculating ahsā is of the pattern of af‘al meaning ‘more precise’ what they had tarried li-mā labithū is semantically …

Excerpt from Tafsir al-Jalalayn, commentary on 18:12, via Quran.com. The reader has the full commentary and 9 more tafsirs.