I would not keep a hundred dollars because god is watching and he will be mad. What if the hundred dollars belonged to a homeless person and that was all of his money.You would be robbing someone and they would starve to death and his wad of cash was gone. If you take it you will be guilty for the rest of your life and maybe make a family starve to death. If you take it to the person who lost the money god and you  would do something good for a person and maybe a family. It’s a dacent amount of money but do the right thing. Are you convinced to take the money or are you going to be a good person.