Surah Ar-Ra'd — Ayah 28 (13:28)
ٱلَّذِينَ ءَامَنُواْ وَتَطۡمَئِنُّ قُلُوبُهُم بِذِكۡرِ ٱللَّهِۗ أَلَا بِذِكۡرِ ٱللَّهِ تَطۡمَئِنُّ ٱلۡقُلُوبُ ٢٨
English translation (Saheeh International)
Those who have believed and whose hearts are assured by the remembrance of Allāh. Unquestionably, by the remembrance of Allāh hearts are assured."
Brief commentary
These people whom Allah guides are those who have faith and whose hearts find comfort in the remembrance of Allah and in His glorification and praise and by reciting and listening to His book. Truly it is only natural that in the remembrance of Allah hearts find comfort.