Mark 9:2-4 - His clothes became dazzling white

9:2

Why did this event take place? It was probably to reassure Peter, James and John in light of the revelations that Jesus had just given to them, or six days earlier to be precise. Jesus allowed the implications of His teaching about His own suffering, and their subsequent sharing in that suffering. It is worth noting that Jesus’ teaching on the resurrection seems to have completely passed them by. So Jesus leads the three of them up “a high mountain”, this is commonly identified with Mount Hermon, though some have said it was Mount Tabor. On this mountain Jesus “was transfigured before them”. This was something that was done to Jesus, rather than something He did Himself.

9:3,4

Jesus’ clothes became a “dazzling white”,”whiter than anyone in the world could bleach them”. I.e there was something supernatural about the change in appearance. Elijah and Moses appeared as well, and they were talking with Jesus. Moses and Elijah are taken as representing the Law and the Prophets. In Mal 4:5 Elijah is associated with the end times. God is telling the three (and us) that in Christ all the plans of the Old Testament are fulfilled. Jesus said that He had come to fulfil the Law and the Prophets (Matt 5:17).