الَّذِينَ آمَنُوا وَتَطْمَئِنُّ قُلُوبُهُم بِذِكْرِ اللَّهِ ۗ أَلَا بِذِكْرِ اللَّهِ تَطْمَئِنُّ الْقُلُوبُ (28)
(13:28) Such are the people who have accepted (the Message of this Prophet,) and their hearts find comfort in the remembrance of Allah. Note it well that it is Allah's remembrance alone that brings comfort to hearts.