Rashi on Isaiah
the vision of everything All that you used to see in the constellations shall be concealed from you like the words of a letter sealed with wax, which, if they give to read one able to read a letter, he will say, “I cannot, for I see not what is inside, for it is sealed.”
Ibn Ezra on Isaiah
For it is sealed. They cannot understand it; the same meaning is contained in the words, seal the law (8:16),17God told the prophet to leave the prophecy for the present unexplained. as I explained.