According to passages in the New Testament of the Holy Bible, such as Matthew 17:1-13, Mk 9:2 and Lk 9:28, Peter, James and John (the disciple) assist to Jesus' transfiguration on "the mountain". In the Christian tradition, that mountain is represented by Tabor, which is also referred to as "the mountain" in other Biblical texts.
In Matthew 17:1-13, we are told that Jesus took three of his disciples, namely Peter, James and John his brother, and took them to a high mountain. He was transfigured in their presence, namely His face shone like the sun and His clothes got as white as the light. There appeared also Elias and Moses, and they talked to Jesus.
At this point, Peter spoke to Jesus and offered to make three tabernacles (a sort of tents), one for each of them: Jesus, Elias and Moses. And as Peter was still speaking, there came a shiny cloud over them, and a voice was heard from inside that cloud, saying: "This is my beloved Son, in whom I am well pleased; hear ye Him."
The Bible attests that upon hearing that voice, Jesus' disciples got terrified and fell down on their knees, their faces to the ground. Also, Jesus came to comfort them, and told them not to be afraid. When Peter, John and James raised their eyes, they saw only Jesus, the other two were gone.
And when they came down from the mountain, they were urged by Jesus not to tell anyone about this until His resurrection. So this is the account of the Transfiguration episode, as it is presented in the Gospel of Matthew.
This episode came to assert once again Jesus' true identity in the eyes of the apostles - as the Son of God, who shall later on spread the account of this event which was certainly unforgettable to them, to all the future believers.
Not all the people agree that this was the exact place in which the Transfiguration occurred. The argument against this is that there was an army fort there which had prevented this place from being chosen by Jesus.
So in the time of our Savior, this hill may have become deserted, which allowed Him to use this location as a place of rest, meditation and prayer during the moment of His transfiguration.
Starting with the 4th century, Christians began real pilgrimages to this place, identifying one rock there with the very place in which the grand event of the Transfiguration happened.
Mount Tabor is also important for the Israeli, due to the fact that Moses blessed it and said that this would be a place where people would come to bring lawful sacrifices to God. (see Deuteronomy: 33,18-19).
The thing about this mountain is that, like all the Holy places in Israel, it does indeed have a beautiful landscape, which seems again to confirm that it was chosen with a Godly taste. Mount Tabor lies about 9km on the east of Nazareth, and on the northeast of Yizrael (Jezreel) Valley.
It is a round and rather steep hill, situated at 613m above the sea level, and 460m above the valley level. Although it looks like an extinct volcano, it has nothing to do with volcanic eruptions.
In the old times, this was an important location also because of the several roads that crossed it: Beit Shean via Ein Dor, Via Maris, Jordan valley (via the Tabor creek), and so on. There is a splendid view over the valley of Jezreel from the top of the hill.
The significance of this mountain is also relevant if we consider the Old Testament of the Bible. Thus, there are many passages mentioning Mount Tabor such as: Joshua 19:22, Judges 4:6, Judges 4:12, Jeremiah 46:18, Josiah 5:1.
But perhaps the Old Testament passage which is most related to the Transfiguration episode that is to be found in the New Testament, can be read in Psalms 89:12 "You created the north and the south; Tabor and Hermon sing for joy at Your Name."