The Wolf and the Crane
As told by Aesop
A wolf was eating the body of an animal he had killed when a small bone got stuck in his throat. He could not swallow it down and he could not cough it up, and the pain of it grew worse and worse. He ran up and down howling and begging every animal he met to help him.
He met a crane and made her a great offer if she would put her long beak down his throat and pull the bone out. The crane was afraid of his teeth, but he swore so many oaths that he meant her no harm, and he promised her so rich a reward, that at last she agreed. He lay on his back and opened his mouth as wide as he could. The crane stretched her neck down and reached the bone with her bill and drew it out.
When she had done this, she asked him for the reward he had promised. The wolf grinned and showed her all his teeth. "Reward?" he said. "You ungrateful bird. You had your head between the jaws of a wolf, and you were allowed to take it out again in safety. Is that not reward enough? Be off, and do not ask me for anything more."
Those who do a kindness to wicked people should not expect to be paid back, except by being allowed to live.