אִ֥ם תִּכְתּֽוֹשׁ־אֶת־הָאֱוִ֨יל ׀ בַּֽמַּכְתֵּ֡שׁ בְּת֣וֹךְ הָ֭רִיפוֹת בַּֽעֱלִ֑י לֹא־תָס֥וּר מֵ֝עָלָ֗יו אִוַּלְתּֽוֹ׃ (פ)
Though thou shouldest bray a fool in a mortar with a pestle among groats, Yet will not his foolishness depart from him.
Read halakhic rulings (Jewish law) on Proverbs 27:22: and classical halakhic sources.