They are the ones whose hearts rejoice in remembering God. Absolutely, by remembering God, the hearts rejoice.
الَّذينَ ءامَنوا وَتَطمَئِنُّ قُلوبُهُم بِذِكرِ اللَّهِ أَلا بِذِكرِ اللَّهِ تَطمَئِنُّ القُلوبُ
allazeena aamanoo wa tatma’innu quloobuhum bizikril laah; alaa bizikril laahi tatma’innul quloob