Knowing this first, that no prophecy of Scripture is of any private interpretation, for prophecy never came by the will of man, but holy men of God spoke as they were moved by the Holy Spirit.
The apostle Peter had just recounted the memorable Transfiguration that he had been an eyewitness of during Christ’s ministry. At that time he had heard a voice from heaven confirming, “This is My beloved Son, in whom I am well pleased” (verses 16-19).
This awesome vision confirmed so many of the Old Testament prophecies of the Messiah. In this context, Peter makes the point that all the prophecies were inspired by God through the Holy Spirit. Many of the prophets didn’t even want the job, and they certainly didn’t make up their messages. God inspired the biblical writers, and He is also the source of proper biblical understanding.
To understand more about God’s purposes for prophecy, see our article “Purpose of Prophecy.”