Rashi on Isaiah
they have become very proud Heb. גֵּא מְאֹד, [lit.] he has become very proud.
Ibn Ezra on Isaiah
We have heard. The prophet represents now the Israelites or the other nations as speaking.
Rashi on Isaiah
their pride and their haughtiness are improper, for the source of the nurturing of their branches was through illegitimacy and the incest of the daughters from their father.