The letter in the story - The Bet by Anton Chekov isiasi follows.
The contents of the letter shows that the lawyer was about to win the bet amount from the banker. However, the lawyer was living in solitary confinement and he was so tired of this battle that he wanted to forfeit the bet amount to live a harmless and peaceful life. He didn't needed the money nor could he care about it. He has reached a state where it doesn't affect him much.