"While he yet spake, behold, a bright cloud overshadowed them:and behold a voice out of the cloud, which said, This is my beloved Son, in whom I am well pleased; hear ye him. And when the disciples heard it, they fell on their face, and were sore afraid. And Jesus came and touched them, and said, Arise, and be not afraid." (Matt 17:5-7)
At the transfiguration of Jesus the Disciples were in awe, but Peter still had a plan. At the announcement of Jesus his plan became inconsequential. The awe of the very voice of God was more than they could bear.
We see many examples very much like this throughout the Bible. Job (Job 40-42), Isaiah (Isa 6:1-8), Daniel (Dan 10:8-10), all men who were declared to be among the greatest of history who covered their mouths and refused to speak or fell before the presence of God and could not get up. All their standing among men became as nothing before the awesomeness of God.
Contrast this with the presence of God before Israel
"And all the people saw the thunderings, and the lightnings, and the noise of the trumpet, and the mountain smoking:and when the people saw it, they removed, and stood afar off. And they said unto Moses, Speak thou with us, and we will hear:but let not God speak with us, lest we die. And Moses said unto the people, Fear not:for God is come to prove you, and that his fear may be before your faces, that ye sin not. And the people stood afar off, and Moses drew near unto the thick darkness where God was" (Ex 19:18-21) (Dt 4-5)
Those undone can step back and stay in their mundaneness, or they can do as Moses and receive from God what he freely gives. This awesome experience is not reserved for a select few, but for all who come before the living God who speaks from Heaven.
"For ye are not come unto the mount that might be touched, and that burned with fire, nor unto blackness, and darkness, and tempest, And the sound of a trumpet, and the voice of words; which voice they that heard intreated that the word should not be spoken to them any more: (For they could not endure that which was commanded, And if so much as a beast touch the mountain, it shall be stoned, or thrust through with a dart: And so terrible was the sight, that Moses said, I exceedingly fear and quake)
But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect, And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel" (Heb 12:18-23)
"Wherefore we receiving a kingdom which cannot be moved, let us have grace, whereby we may serve God acceptably with reverence and godly fear: For our God is a consuming fire" (Heb 12:28-29)
"And when he was demanded of the Pharisees, when the kingdom of God should come, he answered them and said, The kingdom of God cometh not with observation: Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you" (Luke 17:20-21)
"Stand in awe, and sin not:
commune with your own heart upon your bed, and be still. Selah.
Offer the sacrifices of righteousness,
and put your trust in the Lord" (Psalm 4:4-5)
So as for those who have heard the call, who have discarded their old life, taking no thought for the past and with no trust in their own ability to speak or stand on their own, those who have encountered the greatness of our God, he has a further promise:
"Thou hast put gladness in my heart,
more than in the time that their corn and their wine increased" (Psalm 4:7)
Oh the joy and the goodness of our God, great and mighty is his name!