Surah Ar-Ra'd 13:28

ٱلَّذِينَ ءَامَنُوا۟ وَتَطْمَئِنُّ قُلُوبُهُم بِذِكْرِ ٱللَّهِ ۗ أَلَا بِذِكْرِ ٱللَّهِ تَطْمَئِنُّ ٱلْقُلُوبُ

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

Tafsir

those who believe and whose hearts are reassured find rest by God’s remembrance that is by His promise of reward. Verily by God’s remembrance are hearts reassured that is the hearts of the believers;

Excerpt from Tafsir al-Jalalayn, commentary on 13:28, via Quran.com. The reader has the full commentary and 9 more tafsirs.