וּמַלְתֶּ֕ם אֵ֖ת עָרְלַ֣ת לְבַבְכֶ֑ם וְעָ֨רְפְּכֶ֔ם לֹ֥א תַקְשׁ֖וּ עֽוֹד׃
Circumcise therefore the foreskin of your heart, and be no more stiffnecked.
Flames of Faith
Perhaps it is these two classes of kelippos that are referred to in the following verse: U-maltem es orlas livavchem, ve-arpechem lo takshu od, “And you shall circumcise the foreskin of your heart and you should not harden your stubbornness any further” (Deut. 10:16).