Definition of 巧言令色鮮し仁
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(exp) those who resort to blandishments and fawning smiles are apt to lack compassion; a honeyed tongue with a heart of gall
あいつは口ばかりで、誠意がないね。巧言令色少なし仁とはよくいったもんだ。
They say fine words are no virtue if they're insincere and that's him in a nutshell. He's all talk but doesn't mean a word of it.