A Wolf stayed with a flock of sheep until the Shepherd started to ignore him. With that opportunity the Wolf struck and had his meal.
Don’t trust your enemy to guard your valuables.
Aesop For Children
A Wolf had been prowling around a flock of Sheep for a long time, and the Shepherd watched very anxiously to prevent him from carrying off a Lamb. But the Wolf did not try to do any harm. Instead he seemed to be helping the Shepherd take care of the Sheep. At last the Shepherd got so used to seeing the Wolf about that he forgot how wicked he could be.
One day he even went so far as to leave his flock in the Wolf’s care while he went on an errand. But when he came back and saw how many of the flock had been killed and carried off, he knew how foolish to trust a Wolf.
Once a wolf, always a wolf.
A wolf followed a flock of sheep for a long time and did not attempt to injure one of them. The Shepherd at first stood on his guard against him, as against an enemy, and kept a strict watch over his movements. But when the Wolf, day after day, kept in the company of the sheep and did not make the slightest effort to seize them, the Shepherd began to look upon him as a guardian of his flock rather than as a plotter of evil against it; and when occasion called him one day into the city, he left the sheep entirely in his charge. The Wolf, now that he had the opportunity, fell upon the sheep, and destroyed the greater part of the flock. When the Shepherd returned to find his flock destroyed, he exclaimed: “I have been rightly served; why did I trust my sheep to a Wolf?’
Pastor et Lupus Familiaris
Lupus, ovium gregem sequens, nullum iis damnum inferebat. Pastor itaque primo quidem ab eo, tamquam ab hoste, sibi cavebat metuensque illum attente observabat. Deinde vero, licet continuo sequeretur, cum nihil umquam rapere aggressus esset, tunc pastor, eum custodem potius quam insidiatorem esse ratus, postquam necessitate quadam se in urbem conferre adactus est, relictis ei ovibus discessit. Tum lupus, occasione arrepta, maiorem gregis partem devoravit. Reversus inde pastor, gregisque cladem cernens, “Ego quidem digna patior,” inquit; “quid enim lupo oves credidi?”