someone's bark is worse than their bite
(one's) bark is worse than (one's) bite
One's words or demeanor is worse than one's actual behavior. Mr. Stewart may yell a lot, but his bark is worse than his bite—he's actually helped me carry my groceries many times. Don't worry about Sarah's threats. Her bark is worse than her bite.
someone's bark is worse than their bitesomeone is not as ferocious as they appear or sound.
A similar association between barking and biting occurs in the proverb a barking dog never bites , which can be traced back through 13th-century French (chascuns chiens qui abaie ne mort pas , dogs that bark don't bite) to Latin (canem timidum vehementius latrare quam mordere , a timid dog barks more furiously than it bites).