اتق شر الحليم اذا غضب بالانجليزي

اتق شر الحليم اذا غضب. It would literally be “be wary of the wickedness of
the good-natured person if/when he becomes angry.”

At the moment I can’t think of an equivalent proverb in English, but the idea
of “beware of the quiet/nice ones” is a common one, especially when someone commits a
crime who you would not expect to commit a crime.

As an aside, it reminds me of the proverb “تحت السواهي دواهي” which is not
the same of course, but has a related idea. That one is roughly equivalent to
the English proverb “still waters run deep.” If I think of