21 or from human initiative. No, those prophets were moved by the Holy Spirit, and they spoke from God.

Matthew Henry's Commentary on 2 Peter 1:21

Commentary on 2 Peter 1:16-21

(Read 2 Peter 1:16-21)

The gospel is no weak thing, but comes in power, Acts 26:28. God is well pleased with Christ, and with us in him. This is the Messiah who was promised, through whom all who believe in him shall be accepted and saved. The truth and reality of the gospel also are foretold by the prophets and penmenof the Old Testament, who spake and wrote under influence, and according to the direction of the Spirit of God. How firm and sure should our faith be, who have such a firm and sure word to rest upon! When the light of the Scripture is darted into the blind mind and dark understanding, by the Holy Spirit of God, it is like the day-break that advances, and diffuses itself through the whole soul, till it makes perfect day. As the Scripture is the revelation of the mind and will of God, every man ought to search it, to understand the sense and meaning. The Christian knows that book to be the word of God, in which he tastes a sweetness, and feels a power, and sees a glory, truly divine. And the prophecies already fulfilled in the person and salvation of Christ, and in the great concerns of the church and the world, form an unanswerable proof of the truth of Christianity. The Holy Ghost inspired holy men to speak and write. He so assisted and directed them in delivering what they had received from him, that they clearly expressed what they made known. So that the Scriptures are to be accounted the words of the Holy Ghost, and all the plainness and simplicity, all the power and all the propriety of the words and expressions, come from God. Mix faith with what you find in the Scriptures, and esteem and reverence the Bible as a book written by holy men, taught by the Holy Ghost.