@Mukiri, why ask? Or you want the one below?
Saying: The prophet (saw) says with great sorrow:
"The people of my umma will enter hellfire because they take minor sins for granted therefore it becomes a habit for them"
Meaning: When we take sins for granted we ruin our character.
You know we tell our children don't lie, why are we so harsh on that? We are so careful that our children at the young age 4 or 5 or 6 years old we teach them not to lie or to steal and we punish them.
Why? Because we don't want this habit to develop in them they are just children. Tey may lie once or twice it's okay not a big deal, no one is going to hold it against them, they are just children.
But we're afraid of the habit, it becomes a routine and so they become liars, they become cheats, they become thieves.
Similarly, Islam forbid minor sins because of the same reason.
So some people have false hope "God will forgive me"