The Wolf and the Crane - Aesop's fables

The good crane takes pity on the anguished wolf who is in trouble and removes a bone lodged in his throat. But the ungrateful wolf denies the crane his well-deserved reward and spurns the crane after he is saved. The moral of this story is simple; never trust a scoundrel and it is foolhardy to believe that a villain will ever reward you for a job well done.