Then Peter said to Jesus in reply, “Rabbi, it is good that we are here! Let us make three tents: one for you, one for Moses, and one for Elijah.” He hardly knew what to say, they were so terrified. Then a cloud came, casting a shadow... Mark 9:5–7
Peter and his companions had been overcome by sleep, but becoming fully awake, they saw his glory and the two men standing with him. Luke 9:32–33
“I tell you that Elijah has already come, and they did not recognize him but did to him whatever they pleased. So also will the Son of Man suffer at their hands.” Matthew 17:12–13