“Those who believe (in Allah) and their hearts acquire tranquillity with the remembrance of Allah. 

Hear well! It is only through the remembrance of Allah that hearts acquire tranquillity” (13:28)

 وَاذْكُرُوا اللَّهَ كَثِيرًا لَعَلَّكُمْ تُفْلِحُونَ

"Remember Allah abundantly, in order that you become successful" 

(8:45)