Suuratur Ra’ad Verse 28
ٱلَّذِينَ ءَامَنُوا۟ وَتَطْمَئِنُّ قُلُوبُهُم بِذِكْرِ ٱللَّـهِ ۗ أَلَا بِذِكْرِ ٱللَّـهِ تَطْمَئِنُّ ٱلْقُلُوبُ ﴿٢٨
28. Those who believe (in the Oneness of Allaah), and whose hearts find rest in the remembrance of Allaah, Verily, in the remembrance of Allaah do hearts find rest .
Tafsir Ibn Kathir
Allaah said,
﴿الَّذِينَ ءَامَنُواْ وَتَطْمَئِنُّ قُلُوبُهُمْ بِذِكْرِ اللَّهِ﴾
(Those who believed, and whose hearts find rest in the remembrance of Allaah) for their hearts find comfort on the side of Allaah, become tranquil when He is remembered and pleased to have Him as their Protector and Supporter. So Allaah said,
﴿أَلاَ بِذِكْرِ اللَّهِ تَطْمَئِنُّ الْقُلُوبُ﴾
(Verily, in the remembrance of Allaah do hearts find rest) and surely, He is worthy of it.