It is "avoir" in the imperative for "vous" and it is also the subjunctive present form when it has its pronoun.
In other sentences a prepositional phrase "Don't be afraid of ..." was used. Why not in this case?
"Don't be afraid of saying what you think" should be OK, I reckon.
Don't fear to say what you think bounced incorrect...
to tell instead of say marked wrong
what is wrong with 'don't be frightened to say what you think'?
~"Don't be frightened to say what you think" should be accepted
Your mom is hot and I have been sleeping with your sister for over a year now, done :P
Who? Me? 😇