אִ֤ישׁ מֵרֵעֵ֙הוּ֙ הִשָּׁמֵ֔רוּ וְעַל־כָּל־אָ֖ח אַל־תִּבְטָ֑חוּ כִּ֤י כָל־אָח֙ עָק֣וֹב יַעְקֹ֔ב וְכָל־רֵ֖עַ רָכִ֥יל יַהֲלֹֽךְ׃
Take ye heed every one of his neighbour, And trust ye not in any brother; For every brother acteth subtly, And every neighbour goeth about with slanders.
Read halakhic rulings (Jewish law) on Jeremiah 9:3: and classical halakhic sources.