Tit for a tat

Before becoming sixth president of USA,Abraham Lincoln was practicing law.Once a rich man became his client for a case.The case was a just a two and a half dollars debt case.A poor customer had borrowed money from the rich man,but still had two and a half dollars of debt left,which he couldnt clear due to problems from many years.
Lawyer Lincoln said,"Why are you sueing the poor man for just two and a half dollars when you are so rich? Let it go.The court expenses will be more than the money you are expecting to win out of this case"
The rich man replied,"I dont care about the expenses.All i want to do is teach the man a lesson."
Lincoln thought for a while and said,"Alright,My fees will be ten dollars if i have to take up your case."
The rich man said,"No issues."
Later Lincoln went to the poor man's home,gave him 5 dollars and said,"Go and pay the debt of that stubborn rich man because he is planning to sue you in the court.But donot tell anyone i gave this money to you!"
The surprised poor man asked,"Who are you and why are you giving me this?"
Lincoln replied,"I am his lawyer and i dont want to waste my time on this case!"