伊索寓言-狼和鹳鹤（The Wolf and the Crane）

A wolf, having a bone stuck in his throat, hired a Crane, for a large sum, to put her head into his throat, and draw out the bone.

When the Crane had extracted the bone, and demanded the promised payment, the Wolf, grinning and grinding his teeth, exclaimed:"Why, you have surely already a sufficient recompense(报酬), in having been permitted to draw out your head in safety from the mouth and jaws of a wolf." 

For the wicked service, don't hope for reward; You are indeed lucky of not being hurt.