[Idiom] The proper expression

[motico]

Hello

I'd like to know the proper expression to describe someone who hasn't the courage to fulfill his threat.

Thank you, ​

 

[IHIVG]

Hello​

I'd like to know the proper expression to describe someone who hasn't the courage to fulfill his threat. ​

Thank you, ​

'All bark but no bite', or 'His bark is worse than his bite'.

all bark and no bite - Wiktionary
[his] bark is worse than his bite | Define [his] bark is worse than his bite at Dictionary.com