הִנֵּ֨ה נָתַ֧תִּי אֶת־פָּנֶ֛יךָ חֲזָקִ֖ים לְעֻמַּ֣ת פְּנֵיהֶ֑ם וְאֶֽת־מִצְחֲךָ֥ חָזָ֖ק לְעֻמַּ֥ת מִצְחָֽם׃
Behold, I have made thy face hard against their faces, and thy forehead hard against their foreheads.
Read kabbalistic (mystical) interpretation of Ezekiel 3:8: and classical mystical sources.