For no prophecy was ever spoken because a man decided to prophesy, but men said what God gave them to say as they were directed by the Holy Spirit. (GWN)
For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit. (ESV)
For prophecy never came by the will of man, but holy men of God spoke as they were moved by the Holy Spirit. (NKJV)