Quran 18:6 — The Cave (Al-Kahf)

You may blame yourself on account of their response to this narration, and their disbelieving in it; you may be saddened.

[18:5] They possess no knowledge about this, nor did their parents. What a blasphemy coming out of their mouths! What they utter is a gross lie.

[18:7] We have adorned everything on earth, in order to test them, and thus distinguish those among them who work righteousness.