Repentance: Breaking the Habit of Sin Book by Omar Suleiman

Imagine having to stand in front of Allah (s.w.t.) and watch the sin being committed in front of you then having to explain it.
Allah (s.w.t.) mentions in surah Ali Imran, verse 135, "And those who, when they commit immorality or wrong themselves [by transgression], remember Allah and seek forgiveness for their sins..." Keep the door of repentance open between you and Allah because He always ready to forgive you.