U sceccu chi si mancia a fichera u viziu si lu lava quannu mori.
The donkey who eats figs is only rid of the habit when he dies.
The humble donkey used to be the work animal of choice in Sicily, able to carry heavy loads and negotiate the mountain terrain common on the island it was a source of pride of every farming family. But a donkey who ate the figs off the fig tree was a real pain as the precious fig was a major part of the Sicilian’s die,t dried out in the sun they were preserved and served as a valuable nourishment in the harsh winters of the last century.
So the Sicilian agricultural and natural world gives us this metaphor, someone who has a bad habit will never give it up.
A guess for an English equivalent … a leopard never changes it’s spots.