Contradiction with Isaiah 31:3
Isaiah 31:3 states that the Egyptians are men and not God, contrasting the reliance on Egypt in Isaiah 30:4.
Isaiah 31:3: Now the Egyptians [are] men, and not God; and their horses flesh, and not spirit. When the LORD shall stretch out his hand, both he that helpeth shall fall, and he that is holpen shall fall down, and they all shall fail together.
Contradiction with Jeremiah 17:5
Jeremiah 17:5 curses those who trust in man, contradicting the reliance on Egyptian help mentioned in Isaiah 30:4.
Jeremiah 17:5: Thus saith the LORD; Cursed [be] the man that trusteth in man, and maketh flesh his arm, and whose heart departeth from the LORD.
Contradiction with Psalm 146:3
Psalm 146:3 advises against putting trust in princes or human beings, contradicting the confidence placed in Egypt in Isaiah 30:4.
Psalm 146:3: Put not your trust in princes, [nor] in the son of man, in whom [there is] no help. [help: or, salvation]
Contradiction with Isaiah 2:22
Isaiah 2:22 advises to stop trusting in mere humans, which contrasts the trust in Egyptian assistance shown in Isaiah 30:4.
Isaiah 2:22: Cease ye from man, whose breath [is] in his nostrils: for wherein is he to be accounted of?
Contradiction with Hosea 7:11
Hosea 7:11 criticizes Israel for turning to Egypt and not to God, contradicting the actions depicted in Isaiah 30:4.
Hosea 7:11: Ephraim also is like a silly dove without heart: they call to Egypt, they go to Assyria.
Contradiction with Isaiah 31:1
Isaiah 31:1 warns against relying on Egypt for help, directly contradicting the portrayal of seeking Egyptian counsel in Isaiah 30:4.
Isaiah 31:1: Woe to them that go down to Egypt for help; and stay on horses, and trust in chariots, because [they are] many; and in horsemen, because they are very strong; but they look not unto the Holy One of Israel, neither seek the LORD!