Mark 9:7 (KJV)

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.

And his raiment became shining, exceeding white as snow; so as no fuller on earth can white them.

And there appeared unto them Elias with Moses: and they were talking with Jesus.

And Peter answered and said to Jesus, Master, it is good for us to be here: and let us make three tabernacles; one for thee, and one for Moses, and one for Elias.

For he wist not what to say; for they were sore afraid.

And suddenly, when they had looked round about, they saw no man any more, save Jesus only with themselves.

And as they came down from the mountain, he charged them that they should tell no man what things they had seen, till the Son of man were risen from the dead.

And they kept that saying with themselves, questioning one with another what the rising from the dead should mean.

And they asked him, saying, Why say the scribes that Elias must first come?

And he answered and told them, Elias verily cometh first, and restoreth all things; and how it is written of the Son of man, that he must suffer many things, and be set at nought.