People of wisdom state:
Whoever recites (or reads) a prayer without permission, Allahu ta'ala gives him rewards (thawab). But whoever recites it with permission, He not only gives him rewards but also the prayer he has recited takes effect. As a matter of fact, once, Hadrat Imam-i Rabbani and his disciples set out for a long journey. On their way they stopped at an inn to spend the night. He told his disciples that a catastrophe was going to befall the inn during the night and ordered them to recite the following prayer three times: "Bismillaahilladhee laa yadurru ma'asmihee shay'un fil ardi wa laa fissamaai wa huwas-samee'ul 'aleem." That night a great fire broke out, burning everything in every room. Yet those who had said the prayer suffered no harm. Only the belongings of a disciple in a room burnt. Hadrat Imam-i Rabbani summoned him and asked, "Why did your belongings burn? Did you not recite this prayer?" He answered, "No, I did not recite it, sir. My friends forgot to tell me it." Because that disciple could not recite it, he sustained damage in the fire.
Those who say the prayer without permission will earn rewards, but they are not guaranteed that it will save them from fire and other disasters. Because the recitation of it is permitted and ordered, Allahu ta'ala creates the intended result for the reciters.
For protection against worries, disasters, mischief, the evil eye, sorcery, and the evils of the oppressors, you should remember the advice of Hadrat Imam-i Rabbani and say this prayer daily, three times in the morning and three times in the evening. Our masters, too, gave us permission and ordered us to recite it. In fact, it is written in Islamic books that an agent (wakil) has the same status as a principal (muwakkil). Activities of the agent are the activities of the principal. In other words, he who recites prayers by order of an Islamic superior is reciting them as the agent of that exalted person. Consequently, the prayers will be as effective as if they were recited by him, thus leading to spiritual help and blessings.
Similarly, performing khatm-i tahlil, that is, saying the Kalima-i Tawhid (La ilaha ill-Allah) seventy thousand times, is highly meritorious. While Hadrat Mazhar-i Jan-i Janan was passing by a grave, he saw that a sinful woman was in fire in her grave. Upon seeing her, he could not take a step forward and stayed put where he was. Saying, "I will present the thawab of khatm-i tahlil to her soul. She will be forgiven by the will of Allah if she has faith," he supplicated as follows, "O my Lord, I recited the Kalima-i Tawhid seventy thousand times, which is now ready for use. I present it to the soul of this female servant of Yours for Your pleasure. Forgive her." Then the fire and torment was stopped, and the grave became a garden of Paradise.
If the Kalima-i Tawhid is repeated seventy thousand times and sent to the soul of a dead or a living person for the sake of Allah, Allahu ta'ala erases all the sins committed by the receiver until that moment. Performing khatm-i tahlil is beneficial for the reciter as well: it will appear in his grave and come to his rescue. If one presents khatm-i tahlil to a dead person who has faith, Allahu ta'ala removes the torment inflicted on him in the grave. What great news to hear!