Mark 9:2-9

And after six days Jesus taketh with him Peter, and James, and John, and bringeth them up into a high mountain apart by themselves: and he was transfigured before them; and his garments became glistering, exceeding white, so as no fuller on earth can whiten them. And there appeared unto them Elijah with Moses: and they were talking with Jesus. And Peter answereth and saith 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 Elijah. For he knew not what to answer; for they became sore afraid. And there came a cloud overshadowing them: and there came a voice out of the cloud, This is my beloved Son: hear ye him. And suddenly looking round about, they saw no one any more, save Jesus only with themselves. And as they were coming down from the mountain, he charged them that they should tell no man what things they had seen, save when the Son of man should have risen again from the dead.