Surah Al-Kahf 18:25

وَلَبِثُوا۟ فِى كَهْفِهِمْ ثَلَـٰثَ مِا۟ئَةٍ سِنِينَ وَٱزْدَادُوا۟ تِسْعًا

And they remained in their cave for three hundred years and exceeded by nine.

Translation: Saheeh International

Tafsir

And they tarried in the Cave three hundred read with tanwīn thalāthami’atin years sinīn is an explicative supplement to thalāthami’atin ‘three hundred’ these three hundred years in the case of the People of the Cave were solar years; …

Excerpt from Tafsir al-Jalalayn, commentary on 18:25, via Quran.com. The reader has the full commentary and 9 more tafsirs.