מִדַּעְתִּ֕י כִּ֥י קָשֶׁ֖ה אָ֑תָּה וְגִ֤יד בַּרְזֶל֙ עָרְפֶּ֔ךָ וּמִצְחֲךָ֖ נְחוּשָֽׁה׃
Because I knew that thou art obstinate, And thy neck is an iron sinew, and thy brow brass;
Read halakhic rulings (Jewish law) on Isaiah 48:4 from the Mishneh Torah and classical halakhic sources, free online.