Quran 18:13 — The Cave (Al-Kahf)

We narrate to you their history, truthfully. They were youths who believed in their Lord, and we increased their guidance.

[18:12] Then we resurrected them to see which of the two parties could count the duration of their stay therein.

[18:14] We strengthened their hearts when they stood up and proclaimed: "Our only Lord is the Lord of the heavens and the earth. We will never worship any other god beside Him. Otherwise, we would be far astray.