לֹ֥א יָדְע֖וּ וְלֹ֣א יָבִ֑ינוּ כִּ֣י טַ֤ח מֵֽרְאוֹת֙ עֵֽינֵיהֶ֔ם מֵהַשְׂכִּ֖יל לִבֹּתָֽם׃
They know not, neither do they understand; For their eyes are bedaubed, that they cannot see, And their hearts, that they cannot understand.
Read halakhic rulings (Jewish law) on Isaiah 44:18: and classical halakhic sources.