St Mark 9:2-8

And his garments became shining and exceeding white as snow, so as no fuller upon earth can make white. And there appeared to them Elias with Moses; and they were talking with Jesus. And Peter answering, said to Jesus: Rabbi, 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 knew not what he said: for they were struck with fear. And there was a cloud overshadowing them: and a voice came out of the cloud, saying: This is my most beloved son; hear ye him. And immediately looking about, they saw no man any more, but Jesus only with them. And as they came down from the mountain, he charged them not to tell any man what things they had seen, till the Son of man shall be risen again from the dead.