Akademik

Кто много сулит, тот мало делает

People who pledge to do much never keep their word. See Кто много обещает, тот ничего не сделает (K)

Var.: Кто много сулит, тот мало даёт

Cf: Big words seldom go with good deeds (Am.). Expect nothing from him who promises a great deal (Am.). Great promises and small performances (Br.). Не that promises much means nothing (Am., Br.). Long on promises, short on performance (Am., Br.). A long tongue has a short hand (Am.). A long tongue is a sign of a short hand (Am., Br.). No greater promisers than those who have nothing to give (Am., Br.)

Русско-английский словарь пословиц и поговорок. Академик.ру. 2013.