Quran 7:171 — The Purgatory (Al-A'araf)

وَإِذ نَتَقنَا الجَبَلَ فَوقَهُم كَأَنَّهُ ظُلَّةٌ وَظَنّوا أَنَّهُ واقِعٌ بِهِم خُذوا ما ءاتَينٰكُم بِقُوَّةٍ وَاذكُروا ما فيهِ لَعَلَّكُم تَتَّقونَ

We raised the mountain above them like an umbrella, and they thought it was going to fall on them: "You shall uphold what we have given you, strongly, and remember the contents thereof, that you may be saved."

[7:170] Those who uphold the scripture, and observe the Contact Prayers (Salat), we never fail to recompense the pious.

[7:172] Recall that your Lord summoned all the descendants of Adam, and had them bear witness for themselves: "Am I not your Lord?" They all said, "Yes. We bear witness." Thus, you cannot say on the Day of Resurrection, "We were not aware of this."