I cannot explain the calligraphy side of it but in a general sense, this could explain it..
"Those who believe, and whose hearts find satisfaction in the remembrance of Allah. for without doubt in the remembrance of Allah do hearts find satisfaction.
The Thunder , Ar-Rad, Chapter #13, Verse #28
O mankind! there hath come to you a direction from your Lord and a healing for the (diseases) in your hearts,- and for those who believe, a guidance and a Mercy.
Yunus, Chapter #10, Verse #57
* Abu Sa`id Al-Khudri and Abu Huraira reported that the Prophet, peace by upon him, said, "When any group of men remember Allah, angels surround them and mercy covers them, tranquility descends upon them, and Allah mentions them to those who are with Him." (Narrated by Muslim, Tirmidhi, Ahmad, Ibn Majah, and Bayhaqi)