Isaiah 7:9 warns Ephraim that unbelief brings instability, directly connected to the pride and coming judgment described here.

Isaiah 10:9-11 shows Assyria's pride in conquering Samaria, mirroring the arrogance of Ephraim in this verse.

Isaiah 46:12 addresses the 'stouthearted', using the same rare term as the 'stoutness of heart' in this passage.

Isaiah 48:4 describes Israel as obstinate with iron neck, paralleling the pride and stubbornness in this verse.

Isaiah 10:12 uses the same phrase 'stout heart' to describe Assyria's pride, which God will punish after using Assyria to judge Israel's pride.

Isaiah 28:2 depicts God's storm-like judgment on Ephraim's pride, the same target as the 'stoutness of heart' in Isaiah 9:9.

Isaiah 17:9 describes the desolation of Israel's cities, a direct outworking of the judgment on their pride in Isaiah 9:9.

Isaiah 26:11 speaks of people who do not see God's hand but will be consumed — reflecting the same pride that leads to judgment in 9:9.

Proverbs 16:18 states that pride precedes destruction, directly echoing the fatal arrogance of Ephraim in Isaiah 9:9.

Malachi 3:13 records Israel's arrogant words against God, the same 'stoutness of heart' that Isaiah 9:9 condemns.

Malachi 4:1 warns that the proud will be burned like stubble, fulfilling the judgment on the pride described in Isaiah 9:9.

1 Peter 5:5 quotes the principle that God opposes the proud, which is exactly the sin of Ephraim in Isaiah 9:9.

2 Kings 18:11 records the Assyrian exile of Israel, the historical consequence of the pride denounced in Isaiah 9:9.

Hosea 5:5 shows pride of Ephraim testifying against them — directly echoing the pride and stoutness of heart in the main verse, linking arrogance to downfall.

Job 21:20 wishes the wicked to see their own destruction — aligning with the idea in 9:9 that the proud will witness God's judgment.

Jeremiah 44:28 promises a remnant will know whose word stands, echoing the same theme of knowledge through judgment.