Charles Spurgeon Commentary 2 Peter 1:17-18

"For he received from God the Father honor and glory, when there was borne such a voice to him by the Majestic Glory, This is my beloved Son, in whom I am well pleased: and this voice we [ourselves] heard borne out of heaven, when we were with him in the holy mount." — 2 Peter 1:17-18 (ASV)

For he received from God the Father honour and glory, when there came such a voice to him from the excellent glory, This is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount.

They were not deceived—neither Peter, nor James, nor John.

There was "such a voice" from God himself, which they literally heard; it was the Father bearing approving witness to the person and work of his only-begotten and well-beloved Son.

For he received from God the Father honour and glory when there came such a voice to him from the excellent glory, this is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount.

Peter was not deceived about that matter; at the time, he and his fellow apostles had been overcome by the overpowering sight, but they all knew that it was no vision, or dream, or delusion, so Peter here speaks very positively concerning it. Why can we not receive the testimony of true witnesses such as Peter and the other apostles who sealed with their life's blood the witness they bore to their Lord and his truth?