This Bible contradiction is from the Skeptic's Annotated Bible.
Matthew 3:7-11 View context
But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come?
Bring forth therefore fruits meet for repentance:
And think not to say within yourselves, We have Abraham to [our] father: for I say unto you, that God is able of these stones to raise up children unto Abraham.
And now also the axe is laid unto the root of the trees: therefore every tree which bringeth not forth good fruit is hewn down, and cast into the fire.
I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and [with] fire:
Luke 7:29-30 View context
And all the people that heard [him], and the publicans, justified God, being baptized with the baptism of John.
But the Pharisees and lawyers rejected the counsel of God against themselves, being not baptized of him.