שָׁ֤וְא ׀ יְֽדַבְּרוּ֮ אִ֤ישׁ אֶת־רֵ֫עֵ֥הוּ שְׂפַ֥ת חֲלָק֑וֹת בְּלֵ֖ב וָלֵ֣ב יְדַבֵּֽרוּ׃
They speak falsehood every one with his neighbour; With flattering lip, and with a double heart, do they speak.
Read halakhic rulings (Jewish law) on Psalms 12:3: and classical halakhic sources.