Sura al-Kahf 18:93

حَتَّىٰٓ إِذَا بَلَغَ بَيْنَ ٱلسَّدَّيْنِ وَجَدَ مِن دُونِهِمَا قَوْمًا لَّا يَكَادُونَ يَفْقَهُونَ قَوْلًا

ḥatta idhā balagha bayna l-saddayni wajada min dūnihimā qawman lā yakādūna yafqahūna qawlan

Until, when he reached (a tract) between two mountains, he found, beneath them, a people who scarcely understood a word.