弱い犬ほどよく吠える (Yowai inu hodo yoku hoeru)

Meaning: People who make the most noise are often the least able to back it up.

Literally: The weaker the dog, the more it barks

Example: “あの人は大声で脅すだけで何もしない。弱い犬ほどよく吠える。” — He only shouts threats and never does anything: barking dogs seldom bite.

Equivalents in English, French, Spanish, German, Italian, and 5 more languages

English: Barking dogs seldom bite
French: Chien qui aboie ne mord pas (literally: A dog that barks doesn't bite)
Spanish: Perro que ladra no muerde (literally: A dog that barks doesn't bite)
German: Hunde, die bellen, beißen nicht (literally: Dogs that bark do not bite)
Italian: Can che abbaia non morde (literally: A barking dog doesn't bite)
Portuguese: Cão que ladra não morde (literally: A barking dog doesn't bite)
Dutch: Blaffende honden bijten niet (literally: Barking dogs don't bite)
Russian: Не той собаки бойся, что громко лает, а той, что исподтишка хватает (Ne toy sobaki boysya, chto gromko laet, a toy, chto ispodtishka khvataet) (literally: Don't fear the dog that barks loudly, fear the one that bites on the sly)
Polish: Pies, który dużo szczeka, nie gryzie (literally: A dog that barks a lot doesn't bite)
Korean: 짖는 개는 물지 않는다 (Jinneun gaeneun mulji anneunda) (literally: A barking dog doesn't bite)