A sharp tongue will cut off its own head.
More Persian Proverbs:
A wolf's repentance died a long time ago.Persian
You can't polish a turd.
Persian
A beggar will always be a beggar even if they give him the whole world as a gift.
Persian
Fear those who do not fear God.
Persian
The loveliest faces are to be seen by moonlight, when one sees half with the eye and half with the fancy.
Persian
One sin is too much, a hundred prayers are not enough.
Persian