Peter said to Jesus, “Rabbi, it is good for us to be here; let us make three tabernacles, one for You, and one for Moses, and one for Elijah.” For he did not know what to answer; for they became terrified. Then a cloud formed, overshadowing them, and a voice came out of the cloud, “This is My beloved Son, listen to Him!” – Mark 9:5-7

At the sight of a transfigured Jesus (along with a glorified Moses and Elijah), an overwhelmed Peter apparently struggled to think of something to say and (true to form) blurted out what immediately came to mind. The Father’s response to Peter’s ignorant suggestion (to build three tabernacles) was an emphatic reminder of the inequality of the three men who stood before him. Yes, Moses was great, and Elijah was profound, but Jesus is the Son! Moses (who represented the Law) and Elijah (who represented the Prophets) found their fulfillment in Christ and God used this moment to direct Peter to an understanding of the Law and Prophets through the lens of Christ.
God was also saying more. He intended Peter to realize that some experiences in life do not need commentary and we are better served by listening. There are times when we must be still and silent in order to know that He is God. Before you preach, ponder.
Do not lose yourself in your everyday work and activities. Rather, lose yourself in God. When you are doing work, let your innermost heart be centered on Him. Live in His presence and abide in Him. Then your work will follow you into eternity, and you will reap a rich harvest. – Basilea Schlink