Contradiction with Matthew 13:13
In this verse, Jesus explains that the parables are given so that people who are not meant to understand will not hear and understand, which contradicts the open invitation in Matthew 13:9 to hear.
Matthew 13:13: Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand.
Contradiction with Proverbs 28:9
This verse implies that those who turn away from hearing the law have their prayers turned into abominations, contradicting the emphasis on the act of hearing in Matthew 13:9.
Proverbs 28:9: He that turneth away his ear from hearing the law, even his prayer [shall be] abomination.
Contradiction with Isaiah 6:9-10
These verses describe God instructing Isaiah to tell the people to hear but not understand, and see but not perceive, which contradicts the invitation to hear in Matthew 13:9.
Isaiah 6:9-10: And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not. [indeed, but understand: or, without ceasing, etc: Heb. in hearing, etc]
Contradiction with John 12:40
It mentions that God has blinded their eyes and hardened their hearts so they wouldn't see with their eyes, nor understand with their heart, implying a contradiction with the call to hear and understand from Matthew 13:9.
John 12:40: He hath blinded their eyes, and hardened their heart; that they should not see with [their] eyes, nor understand with [their] heart, and be converted, and I should heal them.