Al-Kahf · Ayah 41
أَوْ يُصْبِحَ مَآؤُهَا غَوْرًا فَلَن تَسْتَطِيعَ لَهُۥ طَلَبًا
Or its water will become sunken [into the earth], so you would never be able to seek it."
Quran 18:41 (Al-Kahf) · Saheeh International, Noor International Center (QuranEnc v1.1.2)