For he wist not what to answer; for they became sore afraid.
For he wist not what to say; for they were sore afraid.
For he did not [really] know what to say, for they were in a violent fright (aghast with dread).
For he knew not what to answer; for they became sore afraid.
He said this because he didn’t know how to respond, for the three of them were terrified.
And there was a cloud overshadowing them. And a voice came from the cloud, saying: "This is my most beloved Son. Listen to him."
And there was a cloud overshadowing them: and a voice came out of the cloud, saying: This is my most beloved son; hear ye him.