During the earthly ministry of Jesus, He asks His disciples an important question:
Now when Jesus came into the district of Caesarea Philippi, He asked His disciples, “Who do people say that the Son of Man is?” And they said, “Some say John the Baptist, others say Elijah, and others Jeremiah, or one of the prophets.” He said to them, “But who do you say that I am?” Simon Peter answered, “You are the Christ, the Son of the living God.” And Jesus said to him, “Blessed are you, Simon Bar-Jonah, for flesh and blood has not revealed this to you, but My Father who is in heaven.
“And I say to you that you are Peter, and upon this rock I will build My church, and the gates of hell shall not prevail against it.”
-Matthew 16:13-18 (see also Mark 8:27, Luke 9:18)
Three times in the Gospel account, God Himself speaks from heaven endorsing His Son Jesus Christ:
Then Jesus came from Galilee to the Jordan to John, to be baptized by him. But John tried to prevent Him, saying, “I need to be baptized by You, and yet You come to me?” But Jesus answered him, “Let it be so now, for thus it is fitting for us to fulfill all righteousness.” Then he consented. After being baptized, Jesus came up immediately from the water, and behold, the heavens were opened, and he saw the Spirit of God descending like a dove and coming to rest on Him; and behold, a voice from heaven said, “This is My beloved Son, with whom I am well pleased.”
-Matthew 3:13-17 (see also Mark 1:11, Luke 3:22)
And after six days Jesus took with Him Peter and James, and John his brother, and led them up a high mountain by themselves. And He was transfigured before them, and His face shone like the sun, and His clothes became white as light. And behold, Moses and Elijah appeared to them, talking with Him.
Peter said to Jesus, “Lord, it is good that we are here. If You wish, I will make three tents here, one for You, and one for Moses, and one for Elijah.” While he was still speaking, a bright cloud overshadowed them, and behold, a voice from the cloud said, “This is my beloved Son, with whom I am well pleased; listen to Him.” When the disciples heard this, they fell on their faces and were terrified. But Jesus came and touched them, saying, “Rise, and have no fear.” And when they lifted up their eyes, they saw no one but Jesus only.
-Matthew 17:1-8 (see also Mark 9:7, Luke 9:35)
“Now My soul has become troubled; yet what shall I say? ‘Father, save Me from this hour’? But for this purpose I have come to this hour. Father, glorify Your name.” Then a voice came from heaven: “I have glorified it, and I will glorify it again.” So the crowd that stood there and heard it were saying that it had thundered. Others said, “An angel has spoken to Him.” Jesus answered, “This voice has not come for My sake, but for yours.”
Peter recalls the experience he witnessed while on the mountain with Jesus:
For we did not follow cleverly devised myths when we made known to you the power and coming of our Lord Jesus Christ, but we were eyewitnesses of His majesty. For He received honor and glory from God the Father when the voice came to Him from the Majestic Glory, saying, “This is My beloved Son, with whom I am well pleased.” We ourselves heard this voice that came from heaven when we were with Him on the holy mountain.
-2 Peter 1:16-18