“He (Allah) is such that He sent down tranquility into the hearts of the believers, so that they grow more in faith in addition to their (existing) faith- And to Allah belong the forces of the heavens and the earth, and Allah is All-Knowing, All-Wise-“[Mufti Taqi Usmani][48:4]
SubhanAllah, God is always doing the most for us and we’re never grateful. He explains to us that He sent down to us tranquility and calmness into the hearts of the believers to help their faith grow even more. Because when you’re worry free and you’ve got a heart that is calm you tend to do better/more for what you believe in; for your faith!
He is all knowing and all wise; so He knows how humans work and how to go about us, subhanAllah.