"The Weaking of Faith"
At-Tabarani and Al-Hakim narrated that the Messenger of Allah sallallahu `alayhi wa sallam said, what translated means, "Iman wears out in one's heart, just as the dress wears out (becomes thin). Therefore, ask Allah to renew iman in your hearts." Iman, therefore, becomes old and wears out just as the case clothes. In addition, sometimes, the believer's heart becomes cloudy because of committing sins. The Prophet clearly mentioned this later case, when he said, what translated means, "Each heart has its own passing cloud, just as the moon when it is shining and there comes a cloud that replaces its brightness and darkness. Whenever it (the cloud) moves on, it (the moon) will shine yet again." [Abu Nu`am & As-Silsilah As-Sahihah]. Sometimes, a cloud overtakes the moon's brightness and replaces it with darkness, but when this cloud moves on, the moon will become bright and shining again. This is the exact case with the believer's heart, for sometimes a dark cloud overtakes the heart, because of indulging in sin. This dark cloud will prevent the light of Iman from filling the heart and will only go away when one strives hard to increase his Iman, depending on Allah. Then, the cloud will certainly vanish and the heart will once more regain its full health and brightness.
In the process of healing weak Iman, it is important to know that Iman increases with working the good deeds and decreases by indulging in sin, for, according to Ahlu as-Sunnnah wal Jama`ah (who following the Quran, the Sunnah and the understanding of the companions), Iman entails acknowledgement with the tongue, belief in the heart implementing the Commandments. Furthermore, Allah said, what translated means, "That they may grow more in Faith" [48:4], and "Which of you has had his faith increased?" [9:124]
Also, the Messenger of Allah said, what translated means, "He among you who witnesses an evil, let him change (stop, remove) it with his hand, if he could not, then with his tongue, and if he could not, then with his heart, and this is the weakest Iman." [Al-Bukhari] The effect of indulging in sin or performing good deeds is well-known, as Iman in the heart will be affected by experiencing either a decrease or an increase. When one goes to the marketplace and spends the time there looking at women and listening to the often unnecessary speech that people indulge in and then goes to a grave site, he will experience an immediate change in the status of Iman in his heart while he is in the graveyard as compared to when he was at the marketplace.
Some of our righteous Salaf (ancestors) said, "It is a sign of the slave's Fiqh (knowledge of the religion) that he concerns himself with enhancing the status of his Iman when it experiences a decrease. Also, it is a sign of the slave's Fiqh to know if his Iman is on the increase or on the decrease. Furthermore, it is a sign of one's Fiqh that he knows why and where the evil whispers of Satan are coming from."
It is important to know that it is a turn to the worse and a dangerous precedent to let the decrease in Iman that the heart is experiencing lead to abandoning some of the obligations. Such behavior leads one to be among the criticized persons and obliges him to repent to Allah and to immediately start solving the weakness of his Iman. On the other hand, when the decrease in Iman only leads to abandoning some of the preferred acts of worship, then one must strive hard in this case to perform such preferred acts with patience and endurance until his heart regains its health. In this regard, the Messenger of Allah said, what translated means, "With regards to each act of worship, there is a period of increased activity, and after each period of increased activity, there is a period of decreased activity (that follows it). Therefore, if one settles down to that which is a part of my Sunnah, he will be the successful one. As for he who settles down to the opposite, then he is destroyed." [Ahmad and Sahih at-Targhib].
Before we start detailing the manner with which one can cure weak Iman, we should mention that many of those who experience hardness in their hearts search for external cures for this problem. However, such people can solve their weak Iman by themselves, for Iman is a personal matter between the slave and the Lord. Now, we will detail some of the cures for weak Iman that will erase hardness in the heart and will help regain strong Iman, Allah willing.