How can one get rid of feelings of fear and sadness when sensing the approach of death, given the scarcity of good deeds, abundance of sins, and the loneliness of the grave, and how can one find reassurance and have a good opinion of their Lord at such moments?

The feeling that one's end is approaching should motivate good deeds and preparation for the Hereafter. However, it should not lead to despair or distraction from one's work. One must combine fear and hope, for the appointed times of servants are hidden and known only to Allah the Almighty: "Say: None in the heavens and earth knows the unseen except Allah" [An-Naml: 65], and "And no soul can die except by permission of Allah" [Al Imran: 145]. Let the fear of Allah be a motivator for righteous action, for "Whoever fears, journeys at night, and whoever journeys at night, reaches the destination. Verily, the commodity of Allah is expensive. Verily, the commodity of Allah is Paradise." The expansion of the chest comes through monotheism, knowledge, turning to Allah in repentance, frequent remembrance of Allah, and doing good to creation.