וְל֤וֹא שָׁמְעוּ֙ אֵלַ֔י וְלֹ֥א הִטּ֖וּ אֶת־אָזְנָ֑ם וַיַּקְשׁוּ֙ אֶת־עָרְפָּ֔ם הֵרֵ֖עוּ מֵאֲבוֹתָֽם׃
yet they hearkened not unto Me, nor inclined their ear, but made their neck stiff; they did worse than their fathers.
Read kabbalistic (mystical) interpretation of Jeremiah 7:26: and classical mystical sources.