Peter said to Jesus, “Rabbi, it is good for us to be here. Let us put up three shelters — one for you, one for Moses and one for Elijah.”Mark 9:5 NIV
Jesus had taken Peter, James, and John up onto a mountain and was transfigured before them. While there, the three disciples saw Moses and Elijah, talking with Jesus. When Peter saw this he was very frightened, which I can well understand. But he also felt the need to say something. So he offered to put up three shelters, one for Jesus, one for Moses, and one for Elijah.
For a long time, this made little sense to me. Why would he think they needed shelters? But the word the NIV translates as shelter is usually used in the New Testament to refer to the Tabernacle of the Exodus. It was a place of worship. A place to meet with God. I think that this statement from Peter was intended to honor Jesus. He was not just a great teacher. He was on a par with Moses and Elijah, representing the Law and the Prophets. Peter was essentially wanting to put Jesus on the Jewish equivalent of Mt Rushmore by building three tabernacles, one for each of them.
Then a cloud covered them and God spoke from it. And God identified Jesus as his Son, the one they should listen to. And when the cloud was gone, so also were Moses and Elijah. While Peter elevated Jesus to the level of Moses and Elijah, God raised him above them. Moses and Elijah were great men. But Jesus was the Son of God. Rather than cling to Moses and Elijah, listen to Jesus and hold to him.