2 Peter 1:14-18
14Knowing that shortly I must put off this my tabernacle, even as our Lord Jesus Christ hath showed me. 15Moreover I will endeavour that ye may be able after my decease to have these things always in remembrance. 16For we have not followed cunningly devised fables, when we made known unto you the power and coming of our Lord Jesus Christ, but were eyewitnesses of his majesty. 17For 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. 18And this voice which came from heaven we heard, when we were with him in the holy mount.
Comment: Peter is claiming that he had seen Jesus in his glorified state. This incident is recounted in other New Testament texts [cf. Matthew 17:1-9, Mark 9:2-10, Luke 9:28-36] implying that it was a commonly held belief by early Christians and other eyewitnesses of Jesus' miracles. Luke, for example, had to be convinced of its veracity before including it in his book because he claimed that he checked all these things out [cf. Luke 1:1-4]. For other authors to include it in their accounts of Jesus' life also lends veracity to the story. The accounts of the incident indicate there were two other witnesses besides Peter; James and John. The accounts include God's voice stating that Jesus was his son, implying that His power was at Jesus' disposal. Surely, if God's power were at Jesus' disposal, it would not be impossible for Jesus to rise from the grave. Even more credibility is added to Peter's claim to having been a witness of Jesus' glory when he states that he would end up dying for his beliefs. Why, then, would Peter be willing to give his life for something he didn't believe? Plus he used the plural form "we" indicating there were other witness of Jesus' glory and the voice from heaven. Thus we not only have consistency with the other accounts of the incident, but Peter's sincerity in being willing to give his life rather than deny what he had witnessed.