18:25
وَلَبِثُوا۟ فِى كَهْفِهِمْ ثَلَـٰثَ مِا۟ئَةٍ سِنِينَ وَٱزْدَادُوا۟ تِسْعًا
walabithū fī kahfihim thalātha mi-atin sinīna wa-iz'dādū tis'ʿan
[Some say], ‘The sleepers stayed in their cave for three hundred years,’ some added nine more.
And they stayed in their Cave three hundred (solar) years, adding nine (for lunar years). (Tafsir Al-Qurtubi)