Wherefore thus saith the Holy One of Israel, Because ye despise this word, and trust in oppression and perverseness, and stay thereon:
Wherefore thus saith the Holy One. Isaiah so little yields to their wicked prejudices that he repeats the very name and truth which they disliked.
Because ye despise this word - Isaiah's exhortation to reliance on Yahweh.
And trust in oppression - whereby they levied the treasures to be sent to conciliate Egypt (Isaiah 30:6).
And perverseness - in relying on Egypt rather than on Yahweh.