Quran 49:3 — The Walls (Al-Hujurat)

Surely, those who lower their voices at the messenger of GOD are the ones whose hearts are prepared by GOD to become righteous.* They have deserved forgiveness and a great recompense.

[49:2] O you who believe, do not raise your voices above the voice of the prophet,* nor shall you shout at him as you shout at each other, lest your works become nullified while you do not perceive.

[49:4] As for those who call on you from outside the walls, most of them do not understand.