Your Bark is Worse Than Your Bite
Perro que ladra, no muerde
We tell a person that their bark is worse than their bite to mean than their threats are more frightening in sound than what they really are when they are put into practice.
This expression was first used in the mid-1600’s. There are dogs that bark as if they were going to take your soul out of your body with a bite. Actually, dogs which bark the highest usually never attack you. That’s why, when a person announces a threat or a future punishment but in the end, they don´t do anything about it is when we say that their bite is worse than their bite.