ٱلَّذِينَ ءَامَنُواْ وَتَطۡمَئِنُّ قُلُوبُهُم بِذِكۡرِ ٱللَّهِۗ أَلَا بِذِكۡرِ ٱللَّهِ تَطۡمَئِنُّ ٱلۡقُلُوبُ ٢٨
Those who have believed and whose hearts are assured by the remembrance of Allāh. Unquestionably, by the remembrance of Allāh hearts are assured."
Translation: Saheeh International (English)
Each word's meaning and sound
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.
Al-Mukhtasar in interpreting the Noble Quran