A bet on condolence

I was really in doubt about one student: should I reprove him or should I assign another test to him?
I decided to reprove because I do not want that my students think it is easy to get another chance. If he were my child, I would do the same.
He must have had many merciful teachers that gave another chance to him.
He did not show in one test. I suppose he was expecting me to apply almost the same test exclusively to him. In this case, he would be benefited by wrong doing.
I want to show my children and my students that crime does not pay.
However, crime seems to pay for those who do not believe in judgement after death.