Once, a wolf got into the habit of following a flock of sheep without ever attacking any of them.
As a result, after some time the shepherd began to think of the wolf as more of a guardian than an enemy.
One day the shepherd had to go to the city on business and it seemed natural for him to leave his flock in the care of the wolf. When he returned that evening, every single one of his sheep had been killed.
The shepherd thought long and hard over what had happened and in the end realised, that it was completely his own fault.
Whoever puts his faith in wicked friends should expect no better.