Verily in the remembrance of Allah do the hearts find rest / Shaikh Abdu'l-Razzaq Ibn 'Abdu'l-Muhsin al-Badr

Summary

When Alläh, the Almighty, says:
"Verily, in the remembrance of Alläh do hearts find rest." [Sürah ar-R'ad 13:28]
It means that it imparts restfulness and tranquility. When we think about this and the reality of peoples' hearts in this worldly life, it is really complicated a desires, attraction by lusts, suspicions, and seditions; leaving no place for rest it: a sense of loss, displeasure, and annoyance; in short, restlessness. It means that there hearts felt restless, annoyed and lost in which one suffers from suspicions and doubts. All of it are diseases of the heart. No heart can be restful unless with the remembrance of Alläh. If it is free from the remembrance of Alläh, it is vulnerable to be infected with those illnesses. Thus, (سُبْحَانَهُ وتعالى)
"Those who believed (in the Oneness of Alläh - Islamic Monotheism, and whose hearts find rest in the remembrance of Alläh: Verily, in the remembrance of Alläh do hearts find rest."
So, restfulness of hearts is to be happy and tranquil, free from worries and annoyance; this can be achieved by the remembrance of Allah.
Without the remembrance of Alläh, the heart will die. Abu Musa Al-Asha'ri narrated that (صلى اللّهُ عليه وسلّم) o)
"The similitude of one who remembers his Lord and one who does not remember
Him is like that of the living and the dead."