Ibn al-Qayyim (R.A) said:‘A person may commit a sin and enter Paradise because of it, or he may do an act of worship and enter Hell because of it.’ They said: ‘How is that?’ He said: ‘He may commit a sin and continues to think about it and when he stands or sits or walks he remembers his sin, so he feels ashamed and repents and seeks forgiveness and regrets it so that will be the means of his salvation. And he may do a good deed and continue to think about it, and when he stands or sits or walks he remembers it and it fills him with self-admiration and pride, so it is the cause of his doom.