Contradiction with 2 Corinthians 6:14
This verse advises not to make alliances with unbelievers, which contradicts Joshua 9:8 where Joshua listens to the Gibeonites and makes peace with them.
2 Corinthians 6:14: Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
Contradiction with Exodus 23:32
This verse instructs not to make covenants with the inhabitants of the land, whereas in Joshua 9:8, Joshua engages in making a covenant with the Gibeonites.
Exodus 23:32: Thou shalt make no covenant with them, nor with their gods.
Contradiction with Deuteronomy 7:2
This verse commands the Israelites to utterly destroy the nations before them and make no covenants, contrasting with Joshua's actions in Joshua 9:8.
Deuteronomy 7:2: And when the LORD thy God shall deliver them before thee; thou shalt smite them, [and] utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them:
Contradiction with Deuteronomy 20:16-17
These verses command the Israelites to completely destroy certain nations, unlike the treaty made in Joshua 9:8.
Deuteronomy 20:16-17: But of the cities of these people, which the LORD thy God doth give thee [for] an inheritance, thou shalt save alive nothing that breatheth: