Allah said,

﴿الَّذِينَ ءَامَنُواْ وَتَطْمَئِنُّ قُلُوبُهُمْ بِذِكْرِ اللَّهِ﴾

(Those who believed, and whose hearts find rest in the remembrance of Allah.) for their hearts find comfort on the side of Allah, become tranquil when He is remembered and pleased to have Him as their Protector and Supporter. So Allah said,

﴿أَلاَ بِذِكْرِ اللَّهِ تَطْمَئِنُّ الْقُلُوبُ﴾

(Verily, in the remembrance of Allah do hearts find rest.) and surely, He is worthy of it.