all talk, no action
A four-character idiom contrasting with 有言実行 (walking the talk). Used to criticize someone who makes promises or declarations but fails to follow through.
See also: 有言実行 (ゆうげんじっこう)
He's all talk and no action; his plans always fall through.
If you're all talk and no action, you'll just lose people's trust.
The positive counterpart: 'doing what one says,' walking the talk. 有言不実行 is its direct opposite.
A four-character idiom formed by inserting 不 (not) into 有言実行 (walking the talk), creating the opposite meaning. The exact origin is uncertain, but it follows a common pattern of negating established compounds.