dialog to deny and admit something

Deny:
A: Hey friend, are you the person that stole my pencil?
B: No, i am not the guy
A: Just admit it
B: Swear, i don't know anything about your pencil. You can ask the other if they know about your pencil
A: Ok, i will do it.

Admit:
A: Hey friend, are you the person that stole my pencil?
B: No, i am not
A: Just admit it
B: I am sorry, i stole your pencil because i can't afford a pencil
A: I will forgive but promise me you won't do it again
B: Yes, i promise