חֵ֥ץ שוחט [שָׁח֛וּט] לְשׁוֹנָ֖ם מִרְמָ֣ה דִבֵּ֑ר בְּפִ֗יו שָׁל֤וֹם אֶת־רֵעֵ֙הוּ֙ יְדַבֵּ֔ר וּבְקִרְבּ֖וֹ יָשִׂ֥ים אָרְבּֽוֹ׃
Their tongue is a sharpened arrow, It speaketh deceit; One speaketh peaceably to his neighbour with his mouth, But in his heart he layeth wait for him.
Read halakhic rulings (Jewish law) on Jeremiah 9:7: and classical halakhic sources.