What is the reason for my feeling of distress and lack of tranquility when remembering Allah, and my ceasing to perform night prayers (Qiyam al-Layl) and supplications (Du'a), despite my maintaining regular prayers and avoiding sins, and what should I do about this?

The closer a servant draws to Allah, the more Satan confronts him. Therefore, a Muslim must be patient, strive against himself and Satan, and supplicate frequently. Maintaining prayers, avoiding unlawful acts, remembering Allah often, and drawing closer to Him through supererogatory acts are the straight path. Do not despair of supplication, for the Messenger of Allah, peace and blessings be upon him, said: "The supplication of any one of you will be answered as long as he does not supplicate for a sin or for the severance of ties of kinship, and as long as he does not become impatient." So strive in remembrance (dhikr), prayer, and standing in night prayer (qiyam). Sadness, grief, and apathy are from the plots of Satan, so seek refuge in Allah from him. The sweetness of faith is not attained except by striving against oneself and Satan and by persistently performing righteous deeds.