he has eaten so many snakes that has become a viper.
More Persian Proverbs:
As soon as a man gets new trousers, he thinks about a new wife.Persian
The blind man is laughing at the bald head.
Persian
Whether you were gold or satin, you're the same acanthus-seller.
Persian
In your neighbors' soup there is always one fatty morsel.
Persian
Comfortable is he who doesn't have a donkey -- Doesn't know of its straw and barley.
Persian
When a lion is old, he becomes the plaything of jackals.
Persian