Sweet tongue hide black heart.
Largely used in Antigua, this proverb implies that the same person who sweet talks you, will be the same person to betray you.
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A similar proverb from Barbados goes “De tongue dat does buy yuh, does sell yuh.”
In Jamaica, the proverb goes “Oily tung nuh mus tell Di truth,” meaning a smooth talker does not always tell the truth.