וְלֹ֣א שָֽׁמְע֔וּ וְלֹ֥א הִטּ֖וּ אֶת־אָזְנָ֑ם וַיַּקְשׁוּ֙ אֶת־עָרְפָּ֔ם לְבִלְתִּ֣י שומע [שְׁמ֔וֹעַ] וּלְבִלְתִּ֖י קַ֥חַת מוּסָֽר׃
but they hearkened not, neither inclined their ear, but made their neck stiff, that they might not hear, nor receive instruction.
Read kabbalistic (mystical) interpretation of Jeremiah 17:23: and classical mystical sources.