Some argue that the Bible is contradictory concerning after how many days Jesus brought the men up the mountain. The argument is that Matthew 17:1 and Mark 9:2 say that Jesus brought the men up the mountain after six days, but Luke 9:28-29 says that Jesus brought the men up the mountain after eight days. However, the solution to this alleged contradiction in the Bible is simple.
And after six days Jesus took with him Peter and James, and John his brother, and led them up a high mountain by themselves.
Matthew 17:1
And after six days Jesus took with him Peter and James and John, and led them up a high mountain by themselves. And he was transfigured before them,
Mark 9:2
28 Now about eight days after these sayings he took with him Peter and John and James and went up on the mountain to pray. 29 And as he was praying, the appearance of his face was altered, and his clothing became dazzling white.
Luke 9:28-29
Luke’s account says, “about eight days,” while Matthew and Mark’s accounts say, “after six days.” The most likely explanation for why the accounts are different is that Luke is providing an approximate number of days, while Matthew and Mark are providing a more specific number of days.
There is simply no contradiction here because the statements are not mutually exclusive.
There are some foundational principles that apply to all alleged and apparent contradictions in the Bible. To read more, see Bible Difficulties: Foundational Principles.
To read more answers to alleged and apparent contradictions in the Bible, see “Contradictions” in the Bible Answered.
These books are also excellent resources:
Evidence That Demands a Verdict: Life-Changing Truth for a Skeptical World - Josh and Sean McDowell
Little Pilgrim's Progress (Illustrated Edition) - Helen L. Taylor