Contradiction with Luke 7:24-26
These verses describe John as a prophet and more than a prophet, paralleling Matthew 11:9 but focus more on his role, thereby seeming to contradict only if one's interpretation of John's role differs.
Luke 7:24-26: And when the messengers of John were departed, he began to speak unto the people concerning John, What went ye out into the wilderness for to see? A reed shaken with the wind?
Contradiction with John 1:21
John the Baptist denies being a prophet when questioned, which contrasts with the recognition of his prophetic role in Matthew 11:9.
John 1:21: And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. [that prophet: or, a prophet?]
Contradiction with John 10:41
This verse mentions that John did no miracle, which may be seen as contradictory if one equates prophetic greatness with doing miracles.
John 10:41: And many resorted unto him, and said, John did no miracle: but all things that John spake of this man were true.