This Bible contradiction is from the Skeptic's Annotated Bible.
Six days after Jesus foretold his death.
Matthew 16:28 - 17:2 View context
Verily I say unto you, There be some standing here, which shall not taste of death, till they see the Son of man coming in his kingdom.
Mark 9:1-2 View context
And he said unto them, Verily I say unto you, That there be some of them that stand here, which shall not taste of death, till they have seen the kingdom of God come with power.
And after six days Jesus taketh [with him] Peter, and James, and John, and leadeth them up into an high mountain apart by themselves: and he was transfigured before them.
Eight days after Jesus foretold his death.
Luke 9:27-28 View context
But I tell you of a truth, there be some standing here, which shall not taste of death, till they see the kingdom of God.
And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray.