“And Peter said to Jesus, “Lord, it is good that we are here. If you wish, I will make three tents here, one for you and one for Moses and one for Elijah. “He was still speaking when, behold, a bright cloud overshadowed them, and a voice from the cloud said, “This is my beloved Son, with whom I am well pleased, Listen to Him!”
Matthew 17: 4-5

When Jesus took three of His disciples up a high mountain, He was transfigured before them revealing His glorified state. And then Moses and Elijah suddenly appeared talking with Jesus.  Peter’s reaction in seeing them was to make a dwelling place for all three, a place of worship, where God’s presence could stay.

Up until the time of Christ’s appearance, God’s people looked toward the writings of Moses and what the Prophets had foreseen. The religious leaders would often refer to Moses and the Prophets whenever they confronted Jesus. Yet, Jesus told them that it was Moses and the Prophets who identified Who He was and Who the Messiah would be:

“You search the Scriptures because you think that in them you have eternal life: and it is they that bear witness about me, yet you refuse to come to me that you may have life.” John 5:39

When two disillusion disciples left Jerusalem on resurrection day, Jesus appeared to them and opened to them the scriptures:

“And beginning with Moses and all the Prophets, he explained to them what was said in all the Scriptures concerning himself.” Luke 24:27

God immediately responded to Peter who was still looking to what Moses and Elijah had to say, while the one who fulfilled the law and all prophesy was all they needed to hear and see: Matthew 5:17

“He was still speaking when, behold, a bright cloud overshadowed them, and a voice from the cloud said, “This is my beloved Son, with whom I am well pleased, Listen to Him!”

And, “When they looked up, they saw no one except Jesus.”
Matthew 17:8

Resource: Bible Hub: biblehub.com