What is your advice to a person who was accustomed to performing Qiyam al-Layl (night prayer), then abandoned it, then returned to it, then abandoned it again, and now wishes to return to it, but fears that he might abandon it permanently and be deprived of its abundant good? Is this fear of his well-founded, or is it from the whisperings of Satan?

One who has stopped performing Qiyam al-Layl (night prayers) should resume what they have abandoned and accustom themselves to being diligent in it. The fear of abandoning Qiyam in the future is of two types: a satanic fear that leads to abandoning it altogether, and a healthy fear that motivates one to persevere out of apprehension of losing the reward. Among the things that help in perseverance is to take on a portion that one can maintain, and then gradually increase it, for "The most beloved deeds to Allah are those that are continuous, even if they are few." One must be cautious not to abandon the good deeds they have accustomed themselves to, in accordance with the Prophet’s (peace be upon him) prohibition to Abdullah ibn Amr: "O Abdullah, do not be like so-and-so; he used to pray at night, then he stopped praying at night." Frequently turning to Allah and supplicating for success and steadfastness, and reflecting on the virtue of Qiyam al-Layl and one’s shortcomings—all of this helps in perseverance. Among the helpful means is also making up the wird (set portion of prayers/recitations) during the day if it was missed at night, for the Prophet (peace be upon him), if he overslept and missed the night prayer, would pray twelve rak'ahs during the day.